diff --git a/demo/.devcontainer/Dockerfile b/demo/.devcontainer/Dockerfile
new file mode 100644
index 0000000..a746250
--- /dev/null
+++ b/demo/.devcontainer/Dockerfile
@@ -0,0 +1,18 @@
+# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.231.6/containers/ubuntu/.devcontainer/base.Dockerfile
+
+# [Choice] Ubuntu version (use hirsuite or bionic on local arm64/Apple Silicon): hirsute, focal, bionic
+ARG VARIANT="focal"
+FROM mcr.microsoft.com/vscode/devcontainers/base:0-${VARIANT}
+
+# [Optional] Uncomment this section to install additional OS packages.
+# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
+#     && apt-get -y install --no-install-recommends <your-package-list-here>
+
+RUN sudo apt update && apt install -y curl zstd make jq
+
+RUN curl -sL --fail -H "Accept: application/vnd.github.v3+json" \
+    "https://api.github.com/repos/viciious/32XDK/releases/tags/20190504" \
+    | jq -r ".assets | .[] | select(.name | test(\"chillys-sega-devkit-20190504-opt.tar.zst$\")) | .url" \
+    | xargs curl -sL --fail -H "Accept: application/octet-stream" -O /dev/stdout | zstdcat | tar -C / -xa
+
+RUN sudo apt -y install genisoimage
diff --git a/demo/.devcontainer/devcontainer.json b/demo/.devcontainer/devcontainer.json
new file mode 100644
index 0000000..1c59b45
--- /dev/null
+++ b/demo/.devcontainer/devcontainer.json
@@ -0,0 +1,35 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the README at:
+// https://github.com/microsoft/vscode-dev-containers/tree/v0.231.6/containers/ubuntu
+{
+	"name": "Ubuntu",
+	"build": {
+		"dockerfile": "Dockerfile",
+		// Update 'VARIANT' to pick an Ubuntu version: hirsute, focal, bionic
+		// Use hirsute or bionic on local arm64/Apple Silicon.
+		"args": { "VARIANT": "focal" }
+	},
+
+	// Set *default* container specific settings.json values on container create.
+	"settings": {},
+
+
+	// Add the IDs of extensions you want installed when the container is created in the array below.
+	"extensions": [
+		"ms-vscode.cpptools",
+		"steventattersall.m68k",
+		"ms-vscode.cpptools-extension-pack"
+	],
+
+	// Use 'forwardPorts' to make a list of ports inside the container available locally.
+	// "forwardPorts": [],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "uname -a",
+
+	// Comment out to connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode",
+	"features": {
+		"git": "os-provided"
+	}
+
+}
diff --git a/demo/.gitignore b/demo/.gitignore
new file mode 100644
index 0000000..c08d84a
--- /dev/null
+++ b/demo/.gitignore
@@ -0,0 +1,13 @@
+*.elf
+*.map
+*.o
+*.zip
+*.xdelta
+*.iso
+*.cue
+*.elf
+.github
+.vscode
+.cd
+cd
+CDROMPlayer.bin
diff --git a/demo/LICENSE.md b/demo/LICENSE.md
new file mode 100644
index 0000000..63df47f
--- /dev/null
+++ b/demo/LICENSE.md
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 Joseph Fenton
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/demo/Makefile b/demo/Makefile
new file mode 100644
index 0000000..981efca
--- /dev/null
+++ b/demo/Makefile
@@ -0,0 +1,65 @@
+ifdef $(GENDEV)
+ROOTDIR = $(GENDEV)
+else
+ROOTDIR = /opt/toolchains/sega
+endif
+
+LDSCRIPTSDIR = $(ROOTDIR)/ldscripts
+
+BOOTBLOCKDIR = $(ROOTDIR)/bootblocks
+BOOTBLOCK = $(BOOTBLOCKDIR)/US_BOOT.BIN
+#BOOTBLOCK = $(BOOTBLOCKDIR)/EU_BOOT.BIN
+#BOOTBLOCK = $(BOOTBLOCKDIR)/JP_BOOT.BIN
+
+LIBPATH = -L$(ROOTDIR)/m68k-elf/lib -L$(ROOTDIR)/m68k-elf/lib/gcc/m68k-elf/4.6.2 -L$(ROOTDIR)/m68k-elf/m68k-elf/lib
+INCPATH = -I. -I../include -I$(ROOTDIR)/m68k-elf/include -I$(ROOTDIR)/m68k-elf/m68k-elf/include
+
+CCFLAGS = -m68000 -Wall -O1 -c -fomit-frame-pointer
+HWFLAGS = -m68000 -Wall -O1 -c -fomit-frame-pointer
+LDFLAGS = -T $(LDSCRIPTSDIR)/cd.ld -Wl,-Map=output.map -nostdlib
+ASFLAGS = -m68000 --register-prefix-optional
+
+PREFIX = $(ROOTDIR)/m68k-elf/bin/m68k-elf-
+CC = $(PREFIX)gcc
+AS = $(PREFIX)as
+LD = $(PREFIX)ld
+OBJC = $(PREFIX)objcopy
+
+ASMZ80 = $(ROOTDIR)/bin/zasm
+FLAGSZ80 = -vb2
+
+DD = dd
+RM = rm -rf
+
+TARGET = CDROMPlayer
+LIBS = $(LIBPATH) -lc -lgcc -lnosys
+OBJS = crt0.o main.o hw_md.o
+FILES =
+
+all: $(TARGET).bin
+
+$(TARGET).bin: $(TARGET).elf
+	$(OBJC) -O binary $< temp.bin
+	$(DD) if=temp.bin of=$@ bs=2048 conv=sync
+
+$(TARGET).elf: $(OBJS) $(FILES)
+	$(CC) $(LDFLAGS) $(OBJS) $(LIBS) $(FILES) -o $(TARGET).elf
+
+%.o80: %.s80
+	$(ASMZ80) $(FLAGSZ80) -o $@ $<
+
+%.o: %.c
+	$(CC) $(CCFLAGS) $(INCPATH) $< -o $@
+
+%.o: %.s
+	$(AS) $(ASFLAGS) $(INCPATH) $< -o $@
+
+cd: $(TARGET).bin
+	mkdir -p cd
+	mkdir -p cd/ROMs
+	cp $(TARGET).bin cd/APP.BIN
+	cp -r ROMs/* cd/ROMs/
+	genisoimage -sysid "SEGA SEGACD" -volid "CDROMPLAYER" -generic-boot $(BOOTBLOCK) -full-iso9660-filenames -o $(TARGET).iso cd
+
+clean:
+	$(RM) *.o *.o80 *.bin *.elf *.map *.log *.iso cd
diff --git a/demo/README.md b/demo/README.md
new file mode 100644
index 0000000..958847d
--- /dev/null
+++ b/demo/README.md
@@ -0,0 +1,19 @@
+# ROM Loader for the Mega 32X RAM Cart
+
+This project shows an example of how to load files onto the 4MiB RAM cart. 
+
+## Description
+
+Make sure the lower switch on the cart is set to "boot off the CD" position. Write the ISO file of this project to a CD-R and boot using the SegaCD addon.
+
+After initial loading, the program will list files it was able to find on the CD. Select a ROM file from the CD and press A to write it onto the RAM cart. Pressing B will verify ROM/RAM contents with the selected file.
+
+To boot off the previously written ROM, you need to toggle the lower switch to the off position and power cycle the console. Pressing the RESET button on the console will not work!
+
+## "ROM Loader for the Mega 32X RAM Cart" Credits
+* Programming : Chilly Willy and Victor Luchits
+* Base Docker Code : Victor Luchits
+## 
+
+## License
+All original code is available under the MIT license.
diff --git a/demo/ROMs/Mode1PCM.bin b/demo/ROMs/Mode1PCM.bin
new file mode 100644
index 0000000..8b7736e
Binary files /dev/null and b/demo/ROMs/Mode1PCM.bin differ
diff --git a/demo/ROMs/ReadMe.txt b/demo/ROMs/ReadMe.txt
new file mode 100644
index 0000000..00b86ac
--- /dev/null
+++ b/demo/ROMs/ReadMe.txt
@@ -0,0 +1 @@
+Files go in this folder.
\ No newline at end of file
diff --git a/demo/ROMs/TiTAN - Overdrive (Rev1.1-106-Final) (Hardware).bin b/demo/ROMs/TiTAN - Overdrive (Rev1.1-106-Final) (Hardware).bin
new file mode 100644
index 0000000..806640c
Binary files /dev/null and b/demo/ROMs/TiTAN - Overdrive (Rev1.1-106-Final) (Hardware).bin differ
diff --git a/demo/crt0.s b/demo/crt0.s
new file mode 100644
index 0000000..d5ecc0d
--- /dev/null
+++ b/demo/crt0.s
@@ -0,0 +1,45 @@
+| SEGA CD support code
+| by Chilly Willy
+
+        .text
+
+| CD startup at 0x8000
+
+        .global _start
+_start:
+        move    #0x2700,sr              /* disable interrupts */
+
+| Clear BSS
+        lea     __bss_start,a0
+        lea     __bss_end,a1
+        moveq   #0,d0
+1:
+        move.l  d0,(a0)+
+        cmpa.l  a0,a1
+        bhi.b   1b
+
+        move.l  sp,__stack_save         /* save BIOS stack pointer */
+        lea     __stack,a0
+        movea.l a0,sp                   /* set stack pointer to top of Program RAM */
+        link.w  a6,#-8                  /* set up initial stack frame */
+
+        jsr     init_hardware           /* initialize the console hardware */
+
+        jsr     __INIT_SECTION__        /* do all program initializers */
+        jsr     main                    /* call program main() */
+        jsr     __FINI_SECTION__        /* do all program finishers */
+
+        movea.l __stack_save,sp         /* restore BIOS stack pointer */
+        moveq   #0,d0
+        rts
+
+
+        .data
+
+        .align  4
+
+__stack_save:
+        .long   0
+
+        .text
+
diff --git a/demo/files.h b/demo/files.h
new file mode 100644
index 0000000..df56249
--- /dev/null
+++ b/demo/files.h
@@ -0,0 +1,5 @@
+#define NUM_FILES 5
+
+extern char *fileName[NUM_FILES];
+extern int fileSize[NUM_FILES];
+extern int filePtr[NUM_FILES];
diff --git a/demo/files.s b/demo/files.s
new file mode 100644
index 0000000..7f7b3d8
--- /dev/null
+++ b/demo/files.s
@@ -0,0 +1,4 @@
+        .text
+
+        .align  4
+
diff --git a/demo/font.s b/demo/font.s
new file mode 100644
index 0000000..7a39600
--- /dev/null
+++ b/demo/font.s
@@ -0,0 +1,1072 @@
+/* ASCII font from Steph's Mini DevKit */
+
+font_data:
+| 0x20
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0xFFFFFFFF
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0xFFFFFFFF
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x000FF000
+    .long   0x00FFFFF0
+    .long   0x0FF00000
+    .long   0x00FFFF00
+    .long   0x00000FF0
+    .long   0x0FFFFF00
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF0FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FF00FF0
+    .long   0x0F000FF0
+    .long   0x00000000
+
+
+    .long   0x000FFF00
+    .long   0x00FF0FF0
+    .long   0x000FFF00
+    .long   0x00FFF000
+    .long   0x0FF0FFFF
+    .long   0x0FF00FF0
+    .long   0x00FFF0FF
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0000FFF0
+    .long   0x000FFF00
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FFF00
+    .long   0x0000FFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFF0000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FFF000
+    .long   0x0FFF0000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0xFFFFFFFF
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x0FFFFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FF0000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000FF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FF00000
+    .long   0x0F000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF0FFF0
+    .long   0x0FFF0FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x0000FF00
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0000FF00
+    .long   0x000FFF00
+    .long   0x00FFFF00
+    .long   0x0FF0FF00
+    .long   0x0FFFFFF0
+    .long   0x0000FF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x00000FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x00000FF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x00FF0000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000FF0
+    .long   0x0000FF00
+    .long   0x00FFF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FF0000
+
+
+    .long   0x00000FF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x000FF000
+    .long   0x0000FF00
+    .long   0x00000FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x0FF00000
+    .long   0x00FF0000
+    .long   0x000FF000
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FF00000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF0FFF0
+    .long   0x0FF0FFF0
+    .long   0x0FF00000
+    .long   0x00FFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFFF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFF000
+    .long   0x0FF0FF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF0FF00
+    .long   0x0FFFF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFFF0
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF0FFF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFFF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF0FF00
+    .long   0x0FFFF000
+    .long   0x0FFFF000
+    .long   0x0FF0FF00
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF000FF
+    .long   0x0FFF0FFF
+    .long   0x0FFFFFFF
+    .long   0x0FF0F0FF
+    .long   0x0FF000FF
+    .long   0x0FF000FF
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FFF0FF0
+    .long   0x0FFFFFF0
+    .long   0x0FFFFFF0
+    .long   0x0FF0FFF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF0FF00
+    .long   0x00FF0FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x0FF0FF00
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00000
+    .long   0x00FFFF00
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF000FF
+    .long   0x0FF000FF
+    .long   0x0FF0F0FF
+    .long   0x0FFFFFFF
+    .long   0x0FFF0FFF
+    .long   0x0FF000FF
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FF00000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0F000000
+    .long   0x0FF00000
+    .long   0x00FF0000
+    .long   0x000FF000
+    .long   0x0000FF00
+    .long   0x00000FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FFFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x0FFFF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0000F000
+    .long   0x000FFF00
+    .long   0x00FF0FF0
+    .long   0x0FF000FF
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0xFFFFFFFF
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00FFFF00
+    .long   0x0FFFFFF0
+    .long   0x0FFFFFF0
+    .long   0x00FFFF00
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x00000FF0
+    .long   0x00FFFFF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00FFFFF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FFFFFF0
+    .long   0x0FF00000
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x0000FFF0
+    .long   0x000FF000
+    .long   0x00FFFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFFF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000FF0
+    .long   0x0FFFFF00
+
+
+    .long   0x00000000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x00000000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000FF0
+    .long   0x00000000
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00000FF0
+    .long   0x00FFFF00
+
+
+    .long   0x00000000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF0FF00
+    .long   0x0FFFF000
+    .long   0x0FF0FF00
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FFFFFFF
+    .long   0x0FFFFFFF
+    .long   0x0FF0F0FF
+    .long   0x0FF000FF
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FFFFF00
+    .long   0x0FF00000
+    .long   0x0FF00000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFFF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000FF0
+    .long   0x00000FF0
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFF00
+    .long   0x0FF00FF0
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x0FF00000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00FFFFF0
+    .long   0x0FF00000
+    .long   0x00FFFF00
+    .long   0x00000FF0
+    .long   0x0FFFFF00
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x000FF000
+    .long   0x0FFFFFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x0000FFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x000FF000
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF000FF
+    .long   0x0FF0F0FF
+    .long   0x0FFFFFFF
+    .long   0x00FFFFF0
+    .long   0x00FF0FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x00FFFF00
+    .long   0x000FF000
+    .long   0x00FFFF00
+    .long   0x0FF00FF0
+    .long   0x00000000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x0FF00FF0
+    .long   0x00FFFFF0
+    .long   0x0000FF00
+    .long   0x0FFFF000
+
+
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x0FFFFFF0
+    .long   0x0000FF00
+    .long   0x000FF000
+    .long   0x00FF0000
+    .long   0x0FFFFFF0
+    .long   0x00000000
+
+| 7B
+    .long   0x00000000
+    .long   0x0000FFF0
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x0000FFF0
+    .long   0x00000000
+
+| 7C
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 7D
+    .long   0x00000000
+    .long   0x0FFF0000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FFF00
+    .long   0x000FF000
+    .long   0x0FFF0000
+    .long   0x00000000
+
+| 7E
+    .long   0x00000000
+    .long   0x00FFF0FF
+    .long   0x0FF0FFF0
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+| 7F
+    .long   0x0000F000
+    .long   0x000FF000
+    .long   0x00FFF000
+    .long   0x0FFFF000
+    .long   0x00FFF000
+    .long   0x000FF000
+    .long   0x0000F000
+    .long   0x00000000
+
+| 80
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x000FFFFF
+    .long   0x000FFFFF
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 81
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FFFFF
+    .long   0x000FFFFF
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 82
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+| 83
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0xFFFFF000
+    .long   0xFFFFF000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+| 84
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0xFFFFF000
+    .long   0xFFFFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 85
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0xFFFFF000
+    .long   0xFFFFF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 86
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FFFFF
+    .long   0x000FFFFF
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+| 87
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 88
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+
+| 89
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0x000FF000
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+
+| 8A
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0x00000000
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
+    .long   0xFFFFFFFF
diff --git a/demo/hw_md.h b/demo/hw_md.h
new file mode 100644
index 0000000..6a39d9d
--- /dev/null
+++ b/demo/hw_md.h
@@ -0,0 +1,136 @@
+#ifndef _HW_MD_H
+#define _HW_MD_H
+
+#define SEGA_CTRL_BUTTONS   0x0FFF
+#define SEGA_CTRL_UP        0x0001
+#define SEGA_CTRL_DOWN      0x0002
+#define SEGA_CTRL_LEFT      0x0004
+#define SEGA_CTRL_RIGHT     0x0008
+#define SEGA_CTRL_B         0x0010
+#define SEGA_CTRL_C         0x0020
+#define SEGA_CTRL_A         0x0040
+#define SEGA_CTRL_START     0x0080
+#define SEGA_CTRL_Z         0x0100
+#define SEGA_CTRL_Y         0x0200
+#define SEGA_CTRL_X         0x0400
+#define SEGA_CTRL_MODE      0x0800
+
+#define SEGA_CTRL_TYPE      0xF000
+#define SEGA_CTRL_THREE     0x0000
+#define SEGA_CTRL_SIX       0x1000
+#define SEGA_CTRL_NONE      0xF000
+
+/* default text colors */
+#define TEXT_WHITE          0x0000
+#define TEXT_GREEN          0x2000
+#define TEXT_RED            0x4000
+
+/* Z80 control flags */
+#define Z80_BUS_REQUEST     0x0100
+#define Z80_BUS_RELEASE     0x0000
+#define Z80_ASSERT_RESET    0x0000
+#define Z80_CLEAR_RESET     0x0100
+
+#define GET_PAD(p) (*(volatile unsigned short *)(0xFF8018 + p*2))
+#define GET_TICKS (*(volatile unsigned int *)0xFF801C)
+
+// Global Variable offsets - must match boot loader
+typedef struct
+{
+    int VBLANK_HANDLER;
+    int VBLANK_PARAM;
+    int INIT_CD;
+    int READ_CD;
+    int SET_CWD;
+    int FIRST_DIR_SEC;
+    int NEXT_DIR_SEC;
+    int FIND_DIR_ENTRY;
+    int NEXT_DIR_ENTRY;
+    int LOAD_FILE;
+    short DISC_TYPE;
+    short DIR_ENTRY;
+    int CWD_OFFSET;
+    int CWD_LENGTH;
+    int CURR_OFFSET;
+    int CURR_LENGTH;
+    int ROOT_OFFSET;
+    int ROOT_LENGTH;
+    int DENTRY_OFFSET;
+    int DENTRY_LENGTH;
+    short DENTRY_FLAGS;
+    char DENTRY_NAME[256];
+    char TEMP_NAME[256];
+} globals_t;
+
+extern globals_t *global_vars;
+
+// CDFS Error codes - must match boot loader
+enum {
+    ERR_READ_FAILED     = -2,
+    ERR_NO_PVD          = -3,
+    ERR_NO_MORE_ENTRIES = -4,
+    ERR_BAD_ENTRY       = -5,
+    ERR_NAME_NOT_FOUND  = -6,
+    ERR_NO_DISC         = -7
+};
+
+// MD Hardware Calls
+enum {
+    MD_CMD_INIT_HW = 1,
+    MD_CMD_SET_SR,
+    MD_CMD_GET_PAD,
+    MD_CMD_CLEAR_B,
+    MD_CMD_SET_VRAM,
+    MD_CMD_NEXT_VRAM,
+    MD_CMD_COPY_VRAM,
+    MD_CMD_CLEAR_A,
+    MD_CMD_PUT_STR,
+    MD_CMD_PUT_CHR,
+    MD_CMD_DELAY,
+    MD_CMD_SET_PALETTE,
+    MD_CMD_Z80_BUSREQUEST,
+    MD_CMD_Z80_RESET,
+    MD_CMD_Z80_MEMCLR,
+    MD_CMD_Z80_MEMCPY,
+    MD_CMD_DMA_SCREEN,
+    MD_CMD_INIT_32X,
+    MD_CMD_GET_COMM32X,
+    MD_CMD_SET_COMM32X,
+    MD_CMD_DMA_TO_32X,
+    MD_CMD_CPY_TO_32X,
+    MD_CMD_CPY_MD,
+    MD_CMD_END
+};
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int do_md_cmd0(int cmd);
+extern int do_md_cmd1(int cmd, int arg1);
+extern int do_md_cmd2(int cmd, int arg1, int arg2);
+extern int do_md_cmd3(int cmd, int arg1, int arg2, int arg3);
+extern int do_md_cmd4(int cmd, int arg1, int arg2, int arg3, int arg4);
+extern void send_md_cmd0(int cmd);
+extern void send_md_cmd1(int cmd, int arg1);
+extern void send_md_cmd2(int cmd, int arg1, int arg2);
+extern void send_md_cmd3(int cmd, int arg1, int arg2, int arg3);
+extern void send_md_cmd4(int cmd, int arg1, int arg2, int arg3, int arg4);
+extern int wait_md_cmd(void);
+extern void switch_banks(void);
+extern void sub_delay(int cnt);
+
+extern int init_cd(void);
+extern int read_cd(int lba, int len, void *buffer);
+extern int set_cwd(char *path);
+extern int first_dir_sec(void);
+extern int next_dir_sec(void);
+extern int find_dir_entry(char *name);
+extern int next_dir_entry(void);
+extern int load_file(char *filename, void *buffer);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/demo/hw_md.s b/demo/hw_md.s
new file mode 100644
index 0000000..3337912
--- /dev/null
+++ b/demo/hw_md.s
@@ -0,0 +1,1542 @@
+| SEGA MegaCD support code
+| by Chilly Willy
+
+
+|-----------------------------------------------------------------------|
+|                            Sub-CPU code                               |
+|-----------------------------------------------------------------------|
+
+| Global Variable offsets - must match boot loader
+        .equ    VBLANK_HANDLER, 0
+        .equ    VBLANK_PARAM,   4
+        .equ    INIT_CD,        8
+        .equ    READ_CD,        12
+        .equ    SET_CWD,        16
+        .equ    FIRST_DIR_SEC,  20
+        .equ    NEXT_DIR_SEC,   24
+        .equ    FIND_DIR_ENTRY, 28
+        .equ    NEXT_DIR_ENTRY, 32
+        .equ    LOAD_FILE,      36
+        .equ    DISC_TYPE,      40
+        .equ    DIR_ENTRY,      42
+        .equ    CWD_OFFSET,     44
+        .equ    CWD_LENGTH,     48
+        .equ    CURR_OFFSET,    52
+        .equ    CURR_LENGTH,    56
+        .equ    ROOT_OFFSET,    60
+        .equ    ROOT_LENGTH,    64
+        .equ    DENTRY_OFFSET,  68
+        .equ    DENTRY_LENGTH,  72
+        .equ    DENTRY_FLAGS,   76
+        .equ    DENTRY_NAME,    78
+        .equ    TEMP_NAME,      78+256
+        .equ    SIZE_GLOBALVARS,78+256+256
+
+| Disc Read Buffer
+        .equ    DISC_BUFFER, 0x6800
+
+| Program Load Buffer
+        .equ    LOAD_BUFFER, 0x8000
+
+| ISO directory offsets (big-endian where applicable)
+        .equ    RECORD_LENGTH,  0
+        .equ    EXTENT,         6
+        .equ    FILE_LENGTH,    14
+        .equ    FILE_FLAGS,     25
+        .equ    FILE_NAME_LEN,  32
+        .equ    FILE_NAME,      33
+
+| Primary Volume Descriptor offset
+        .equ    PVD_ROOT, 0x9C
+
+| CDFS Error codes
+        .equ    ERR_READ_FAILED,    -2
+        .equ    ERR_NO_PVD,         -3
+        .equ    ERR_NO_MORE_ENTRIES,-4
+        .equ    ERR_BAD_ENTRY,      -5
+        .equ    ERR_NAME_NOT_FOUND, -6
+        .equ    ERR_NO_DISC,        -7
+
+| XCMD Error codes
+        .equ    ERR_UNKNOWN_CMD,    -1
+        .equ    ERR_CMDDONE_TIMEOUT,-2
+        .equ    ERR_CMDACK_TIMEOUT, -3
+
+| MD Hardware Calls - keep in sync with the enums in hw_md.h
+
+        .equ    MD_CMD_INIT_HW, 1
+        .equ    MD_CMD_SET_SR, 2
+        .equ    MD_CMD_GET_PAD, 3
+        .equ    MD_CMD_CLEAR_B, 4
+        .equ    MD_CMD_SET_VRAM, 5
+        .equ    MD_CMD_NEXT_VRAM, 6
+        .equ    MD_CMD_COPY_VRAM, 7
+        .equ    MD_CMD_CLEAR_A, 8
+        .equ    MD_CMD_PUT_STR, 9
+        .equ    MD_CMD_PUT_CHR, 10
+        .equ    MD_CMD_DELAY, 11
+        .equ    MD_CMD_SET_PALETTE, 12
+        .equ    MD_CMD_Z80_BUSREQUEST, 13
+        .equ    MD_CMD_Z80_RESET, 14
+        .equ    MD_CMD_Z80_MEMCLR, 15
+        .equ    MD_CMD_Z80_MEMCPY, 16
+        .equ    MD_CMD_DMA_SCREEN, 17
+        .equ    MD_CMD_INIT_32X, 18
+        .equ    MD_CMD_GET_COMM32X, 19
+        .equ    MD_CMD_SET_COMM32X, 20
+        .equ    MD_CMD_DMA_TO_32X, 21
+        .equ    MD_CMD_CPY_TO_32X, 22
+        .equ    MD_CMD_CPY_TO_MD, 23
+        .equ    MD_CMD_END, 24
+
+        .macro  CD_VCOUNT
+0:
+        move.l  0x801C.w,d0
+        cmp.l   0x801C.w,d0
+        bne.b   0b
+        .endm
+
+        .macro  MD_VCOUNT
+0:
+        move.l  0xA1201C,d0
+        cmp.l   0xA1201C,d0
+        bne.b   0b
+        .endm
+
+        .text
+
+        .align  2
+
+|-----------------------------------------------------------------------
+| Global functions
+|-----------------------------------------------------------------------
+
+| int init_cd(void);
+        .global init_cd
+init_cd:
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        lea     iso_pvd_magic,a5
+        movea.l INIT_CD(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int read_cd(int lba, int len, void *buffer);
+        .global read_cd
+read_cd:
+        move.l  4(sp),d0                /* lba */
+        move.l  8(sp),d1                /* length */
+        movea.l 12(sp),a0               /* buffer */
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l READ_CD(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int set_cwd(char *path);
+        .global set_cwd
+set_cwd:
+        movea.l 4(sp),a0                /* path */
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l SET_CWD(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int first_dir_sec(void);
+        .global first_dir_sec
+first_dir_sec:
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l FIRST_DIR_SEC(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int next_dir_sec(void);
+        .global next_dir_sec
+next_dir_sec:
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l NEXT_DIR_SEC(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int find_dir_entry(char *name);
+        .global find_dir_entry
+find_dir_entry:
+        movea.l 4(sp),a0
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l FIND_DIR_ENTRY(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int next_dir_entry(void)
+        .global next_dir_entry
+next_dir_entry:
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l NEXT_DIR_ENTRY(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int load_file(char *filename, void *buffer);
+        .global load_file
+load_file:
+        movea.l 4(sp),a0                /* filename */
+        movea.l 8(sp),a1                /* buffer */
+        movem.l d2-d7/a2-a6,-(sp)
+        movea.l global_vars,a6
+        movea.l LOAD_FILE(a6),a2
+        jsr     (a2)
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+|-----------------------------------------------------------------------
+| Cross console support
+|-----------------------------------------------------------------------
+
+sub_wait_done:
+        moveq   #0,d0
+        move.b  d0,0x800F.w             /* send md command ACK handshake (for MD_CMD_DMA_SCREEN) */
+        move.w  #0xFFFF,d1
+0:
+        move.b  0x800E.w,d0
+        bmi.b   1f                      /* MD resync request */
+        dbeq    d1,0b                   /* wait on previous md command done */
+        beq.b   2f
+        /* timeout */
+        moveq   #ERR_CMDDONE_TIMEOUT,d0
+1:
+        move.b  d0,0x800F.w             /* xcmd error */
+2:
+        rts
+
+sub_wait_ack:
+        move.w  #0xFFFF,d1
+0:
+        swap    d0
+        move.b  0x800E.w,d0
+        bmi.b   1f                      /* MD resync request */
+        swap    d0
+        cmp.b   0x800E.w,d0
+        dbeq    d1,0b                   /* wait on previous md command done */
+        beq.b   1f
+        /* timeout */
+        moveq   #ERR_CMDACK_TIMEOUT,d0
+1:
+        move.b  d0,0x800F.w             /* xcmd error */
+2:
+        rts
+
+|-----------------------------------------------------------------------
+| Cross console functions
+|-----------------------------------------------------------------------
+
+| int do_md_cmd0(int cmd);
+        .global do_md_cmd0
+do_md_cmd0:
+        move.l  4(sp),d0
+        bsr     send_md_cmd
+        bpl     wait_md_cmd
+        rts
+
+| int do_md_cmd1(int cmd, int arg1);
+        .global do_md_cmd1
+do_md_cmd1:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        bsr     send_md_cmd
+        bpl     wait_md_cmd
+        rts
+
+| int do_md_cmd2(int cmd, int arg1, int arg2);
+        .global do_md_cmd2
+do_md_cmd2:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        bsr     send_md_cmd
+        bpl     wait_md_cmd
+        rts
+
+| int do_md_cmd3(int cmd, int arg1, int arg2, int arg3);
+        .global do_md_cmd3
+do_md_cmd3:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        move.l  16(sp),0x8028.w
+        bsr     send_md_cmd
+        bpl     wait_md_cmd
+        rts
+
+| int do_md_cmd4(int cmd, int arg1, int arg2, int arg3, int arg4);
+        .global do_md_cmd4
+do_md_cmd4:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        move.l  16(sp),0x8028.w
+        move.l  20(sp),0x802C.w
+        bsr     send_md_cmd
+        bpl     wait_md_cmd
+        rts
+
+| void send_md_cmd0(int cmd);
+        .global send_md_cmd0
+send_md_cmd0:
+        move.l  4(sp),d0
+        bra.b   send_md_cmd
+
+| void send_md_cmd1(int cmd, int arg1);
+        .global send_md_cmd1
+send_md_cmd1:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        bra.b   send_md_cmd
+
+| void send_md_cmd2(int cmd, int arg1, int arg2);
+        .global send_md_cmd2
+send_md_cmd2:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        bra.b   send_md_cmd
+
+| void send_md_cmd3(int cmd, int arg1, int arg2, int arg3);
+        .global send_md_cmd3
+send_md_cmd3:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        move.l  16(sp),0x8028.w
+        bra.b   send_md_cmd
+
+| void send_md_cmd4(int cmd, int arg1, int arg2, int arg3, int arg4);
+        .global send_md_cmd4
+send_md_cmd4:
+        move.l  4(sp),d0
+        move.l  8(sp),0x8020.w
+        move.l  12(sp),0x8024.w
+        move.l  16(sp),0x8028.w
+        move.l  20(sp),0x802C.w
+
+send_md_cmd:
+        move.w  d0,-(sp)
+
+        /* wait on previous md command done */
+        bsr     sub_wait_done
+        bmi.b   2f                      /* error - resync */
+
+        move.w  (sp)+,d0
+        move.b  d0,0x800F.w             /* send md command */
+
+        /* wait on md command ACK */
+        bsr     sub_wait_ack
+        bmi.b   1f                      /* error - resync */
+
+        cmpi.b  #MD_CMD_DMA_SCREEN,d0
+        beq.b   1f                      /* no immediate command ACK handshake on MD_CMD_DMA_SCREEN! */
+        move.b  #0,0x800F.w             /* send md command ACK handshake */
+1:
+        rts
+2:
+        addq.l  #2,sp
+        rts
+
+| int wait_md_cmd(void);
+        .global wait_md_cmd
+wait_md_cmd:
+        bsr     sub_wait_done
+        bmi.b   0f                      /* error */
+        move.l  0x8010.w,d0             /* return value */
+0:
+        rts
+
+| void switch_banks(void);
+| Switch 1M Banks
+        .global switch_banks
+switch_banks:
+        bchg    #0,0x8003.w             /* switch banks */
+0:
+        btst    #1,0x8003.w
+        bne.b   0b                      /* bank switch not finished */
+        rts
+
+| void sub_delay(int count);
+| wait count number of vertical blank periods - relies on vblank running
+| entry: arg = count
+        .global sub_delay
+sub_delay:
+        move.l  4(sp),d1                /* count */
+        CD_VCOUNT
+        add.l   d0,d1                   /* add current vblank count */
+1:
+        CD_VCOUNT
+        cmp.l   d0,d1
+        bgt.b   1b
+        rts
+
+| Initialize the SCD hardware & MD code and hardware (called from crt0)
+        .global init_hardware
+init_hardware:
+| init any SCD hardware here
+
+| copy MD code to Word RAM and signal MD side
+        lea     md_init_start(pc),a0
+        lea     0x080000,a1             /* word ram in 2M mode */
+        lea     md_init_end(pc),a2
+1:
+        move.l  (a0)+,(a1)+
+        cmpa.l  a0,a2
+        bhi.b   1b
+        bset    #0,0x8003.w             /* give Main-CPU Word RAM */
+
+        move.b  #'M,0x800F.w            /* send MD Code command to MD */
+2:
+        cmpi.b  #'M,0x800E.w            /* wait for command ACK */
+        bne.b   2b
+        move.b  #0,0x800F.w             /* send command ACK handshake */
+3:
+        tst.b   0x800E.w
+        bne.b   3b                      /* wait on command done */
+
+        bset    #2,0x8003.w             /* switch to 1M mode */
+
+        jsr     0x5F3A.w                /* SPNull - returns boot loader globals */
+        move.l  d0,global_vars
+
+        move    #0x2000,sr              /* allow interrupts */
+        rts
+
+
+|-----------------------------------------------------------------------|
+|                           Main-CPU code                               |
+|-----------------------------------------------------------------------|
+
+| Copied to Word RAM for MD to execute
+        .align  4
+md_init_start:
+        move.b  #'M,0xA1200E            /* md code command ACK */
+
+        lea     md_start(pc),a0
+        lea     0xFF1000,a1
+        lea     md_init_end(pc),a2
+1:
+        move.l  (a0)+,(a1)+
+        cmpa.l  a0,a2
+        bhi.b   1b
+        jmp     0xFF1000
+
+        .align  4
+md_start:
+        move.l  #0,0xA12010
+        move.l  #0,0xA12014
+        move.l  #0,0xA12018
+        move.l  #0,0xA1201C
+        moveq   #0,d7                   /* 32X not initialized */
+        bsr.w   md_init_hw
+cmd_done:
+        tst.b   0xA1200F
+        bmi.b   1f                      /* error - resync */
+        bne.b   cmd_done                /* wait on ACK handshake */
+1:
+        move.b  #0,0xA1200E             /* command done */
+
+        /* main loop */
+        moveq   #0,d0
+cmd_loop:
+        tst.b   d7
+        beq.b   md_check                /* 32X not initialized */
+        move.w  0xA15120,d0
+        beq.b   md_check
+
+        /* handle 32X command */
+        cmpi.w  #1,d0
+        beq.b   md_check                /* copy data to 32X */
+
+
+| unknown command
+
+mars_done:
+        moveq   #0,d0
+        move.w  d0,0xA15120             /* command done */
+md_check:
+        move.b  0xA1200F,d0
+        beq.b   cmd_loop
+        bmi.b   cmd_done                /* error - resync */
+
+        move.b  d0,0xA1200E             /* command ack */
+
+        /* push args on stack */
+        move.l  0xA1202C,-(sp)
+        move.l  0xA12028,-(sp)
+        move.l  0xA12024,-(sp)
+        move.l  0xA12020,-(sp)
+
+        cmpi.b  #'M,d0
+        bne.b   2f
+1:
+        btst    #0,0xA12003            /* Main-CPU has Word RAM? */
+        beq.b   1b
+        jmp     0x200000
+2:
+        cmpi.b  #'I,d0
+        bne.b   3f
+        bset    #1,0xA12003             /* give Sub-CPU Word RAM */
+        bra.b   4f
+3:
+        move.l  #ERR_UNKNOWN_CMD,0xA12010
+        cmpi.b  #MD_CMD_END,d0
+        bhs.b   4f                      /* unknown command */
+        add.w   d0,d0
+        lea     cmd_table(pc),a0
+        move.w  0(a0,d0.w),d0
+        jsr     0(a0,d0.w)
+        move.l  d0,0xA12010             /* return value */
+4:
+        lea     16(sp),sp
+        bra     cmd_done
+
+cmd_table:
+        .word   cmd_done - cmd_table    /* 0 - not really a command */
+        .word   md_init_hw - cmd_table
+        .word   set_sr - cmd_table
+        .word   get_pad - cmd_table
+        .word   clear_b - cmd_table
+        .word   set_vram - cmd_table
+        .word   next_vram - cmd_table
+        .word   copy_vram - cmd_table
+        .word   clear_a - cmd_table
+        .word   put_str - cmd_table
+        .word   put_chr - cmd_table
+        .word   delay - cmd_table
+        .word   set_palette - cmd_table
+        .word   z80_busrequest - cmd_table
+        .word   z80_reset - cmd_table
+        .word   z80_memclr - cmd_table
+        .word   z80_memcpy - cmd_table
+        .word   dma_screen - cmd_table
+        .word   init_32x - cmd_table
+        .word   get_comm32x - cmd_table
+        .word   set_comm32x - cmd_table
+        .word   dma_to_32x - cmd_table
+        .word   cpy_to_32x - cmd_table
+        .word   md_memcpy - cmd_table
+
+| void md_init_hw(void);
+| initialize MD hardware
+md_init_hw:
+        movem.l d2-d7/a2-a5,-(sp)
+        move.w  #0x2700,sr              /* disallow interrupts */
+
+| init joyports
+        lea     0xA10000,a5
+        move.b  #0x40,0x09(a5)
+        move.b  #0x40,0x0B(a5)
+        move.b  #0x40,0x03(a5)
+        move.b  #0x40,0x05(a5)
+
+        lea     0xC00000,a3             /* VDP data reg */
+        lea     0xC00004,a4             /* VDP cmd/sts reg */
+
+| wait on VDP DMA (in case we reset in the middle of DMA)
+        move.w  #0x8114,(a4)            /* display off, dma enabled */
+0:
+        move.w  (a4),d0                 /* read VDP status */
+        btst    #1,d0                   /* DMA busy? */
+        bne.b   0b                      /* yes */
+
+        moveq   #0,d0
+        move.w  #0x8000,d5              /* set VDP register 0 */
+        move.w  #0x0100,d7
+
+| Set VDP registers
+        lea     InitVDPRegs(pc),a5
+        moveq   #18,d1
+1:
+        move.b  (a5)+,d5                /* lower byte = register data */
+        move.w  d5,(a4)                 /* set VDP register */
+        add.w   d7,d5                   /* + 0x0100 = next register */
+        dbra    d1,1b
+
+| clear VRAM
+        move.w  #0x8F02,(a4)            /* set INC to 2 */
+        move.l  #0x40000000,(a4)        /* write VRAM address 0 */
+        move.w  #0x7FFF,d1              /* 32K - 1 words */
+2:
+        move.w  d0,(a3)                 /* clear VRAM */
+        dbra    d1,2b
+
+| The VDP state at this point is: Display disabled, ints disabled, Name Tbl A at 0xC000,
+| Name Tbl B at 0xE000, Name Tbl W at 0xB000, Sprite Attr Tbl at 0xA800, HScroll Tbl at 0xAC00,
+| H40 V28 mode, and Scroll size is 64x32.
+
+| Clear CRAM
+        lea     InitVDPRAM(pc),a5
+        move.l  (a5)+,(a4)              /* set reg 1 and reg 15 */
+        move.l  (a5)+,(a4)              /* write CRAM address 0 */
+        moveq   #31,d3
+3:
+        move.l  d0,(a3)
+        dbra    d3,3b
+
+| Clear VSRAM
+        move.l  (a5)+,(a4)              /* write VSRAM address 0 */
+        moveq   #19,d4
+4:
+        move.l  d0,(a3)
+        dbra    d4,4b
+
+| halt Z80 and init FM chip
+        /* Allow the 68k to access the FM chip */
+        move.w  #0x100,0xA11100
+        move.w  #0x100,0xA11200
+
+| reset YM2612
+        lea     FMReset(pc),a5
+        lea     0xA00000,a0
+        move.w  #0x4000,d1
+        moveq   #26,d2
+5:
+        move.b  (a5)+,d1                /* FM reg */
+        move.b  (a5)+,0(a0,d1.w)        /* FM data */
+        nop
+        nop
+        dbra    d2,5b
+
+        moveq   #0x30,d0
+        moveq   #0x5F,d2
+6:
+        move.b  d0,0x4000(a0)           /* FM reg */
+        nop
+        nop
+        move.b  #0xFF,0x4001(a0)        /* FM data */
+        nop
+        nop
+        move.b  d0,0x4002(a0)           /* FM reg */
+        nop
+        nop
+        move.b  #0xFF,0x4003(a0)        /* FM data */
+        nop
+        nop
+        addq.b  #1,d0
+        dbra    d2,6b
+
+| reset PSG
+        lea     PSGReset(pc),a5
+        lea     0xC00000,a0
+        move.b  (a5)+,0x0011(a0)
+        move.b  (a5)+,0x0011(a0)
+        move.b  (a5)+,0x0011(a0)
+        move.b  (a5),0x0011(a0)
+
+| load font tile data
+        move.w  #0x8F02,(a4)            /* INC = 2 */
+        move.l  #0x40000000,(a4)        /* write VRAM address 0 */
+        lea     font_data(pc),a0
+        move.w  #0x6B*8-1,d2
+7:
+        move.l  (a0)+,d0                /* font fg mask */
+        move.l  d0,d1
+        not.l   d1                      /* font bg mask */
+        andi.l  #0x11111111,d0          /* set font fg color */
+        andi.l  #0x00000000,d1          /* set font bg color */
+        or.l    d1,d0
+        move.l  d0,(a3)                 /* set tile line */
+        dbra    d2,7b
+
+| set the default palette for text
+        move.l  #0xC0000000,(a4)        /* write CRAM address 0 */
+        move.l  #0x00000CCC,(a3)        /* entry 0 (black) and 1 (lt gray) */
+        move.l  #0xC0200000,(a4)        /* write CRAM address 32 */
+        move.l  #0x000000A0,(a3)        /* entry 16 (black) and 17 (green) */
+        move.l  #0xC0400000,(a4)        /* write CRAM address 64 */
+        move.l  #0x0000000A,(a3)        /* entry 32 (black) and 33 (red) */
+
+        lea     vblank_int(pc),a0
+        move.l  a0,0xFFFD08             /* set level 6 int vector */
+
+        move.w  #0x8174,(a4)            /* display on, vblank enabled */
+        movem.l (sp)+,d2-d7/a2-a5
+        move    #0x2000,sr              /* allow interrupts */
+        rts
+
+| VDP register initialization values
+InitVDPRegs:
+        .byte   0x04    /* 8004 => write reg 0 = /IE1 (no HBL INT), /M3 (enable read H/V cnt) */
+        .byte   0x14    /* 8114 => write reg 1 = /DISP (display off), /IE0 (no VBL INT), M1 (DMA enabled), /M2 (V28 mode) */
+        .byte   0x30    /* 8230 => write reg 2 = Name Tbl A = 0xC000 */
+        .byte   0x2C    /* 832C => write reg 3 = Name Tbl W = 0xB000 */
+        .byte   0x07    /* 8407 => write reg 4 = Name Tbl B = 0xE000 */
+        .byte   0x54    /* 8554 => write reg 5 = Sprite Attr Tbl = 0xA800 */
+        .byte   0x00    /* 8600 => write reg 6 = always 0 */
+        .byte   0x00    /* 8700 => write reg 7 = BG color */
+        .byte   0x00    /* 8800 => write reg 8 = always 0 */
+        .byte   0x00    /* 8900 => write reg 9 = always 0 */
+        .byte   0x00    /* 8A00 => write reg 10 = HINT = 0 */
+        .byte   0x00    /* 8B00 => write reg 11 = /IE2 (no EXT INT), full scroll */
+        .byte   0x81    /* 8C81 => write reg 12 = H40 mode, no lace, no shadow/hilite */
+        .byte   0x2B    /* 8D2B => write reg 13 = HScroll Tbl = 0xAC00 */
+        .byte   0x00    /* 8E00 => write reg 14 = always 0 */
+        .byte   0x01    /* 8F01 => write reg 15 = data INC = 1 */
+        .byte   0x01    /* 9001 => write reg 16 = Scroll Size = 64x32 */
+        .byte   0x00    /* 9100 => write reg 17 = W Pos H = left */
+        .byte   0x00    /* 9200 => write reg 18 = W Pos V = top */
+
+        .align  2
+
+| VDP Commands
+InitVDPRAM:
+        .word   0x8104, 0x8F01  /* set registers 1 (display off) and 15 (INC = 1) */
+        .word   0xC000, 0x0000  /* write CRAM address 0 */
+        .word   0x4000, 0x0010  /* write VSRAM address 0 */
+
+FMReset:
+        /* disable LFO */
+        .byte   0,0x22
+        .byte   1,0x00
+        /* disable timer & set channel 6 to normal mode */
+        .byte   0,0x27
+        .byte   1,0x00
+        /* all KEY_OFF */
+        .byte   0,0x28
+        .byte   1,0x00
+        .byte   1,0x04
+        .byte   1,0x01
+        .byte   1,0x05
+        .byte   1,0x02
+        .byte   1,0x06
+        /* disable DAC */
+        .byte   0,0x2A
+        .byte   1,0x80
+        .byte   0,0x2B
+        .byte   1,0x00
+        /* turn off channels */
+        .byte   0,0xB4
+        .byte   1,0x00
+        .byte   0,0xB5
+        .byte   1,0x00
+        .byte   0,0xB6
+        .byte   1,0x00
+        .byte   2,0xB4
+        .byte   3,0x00
+        .byte   2,0xB5
+        .byte   3,0x00
+        .byte   2,0xB6
+        .byte   3,0x00
+
+| PSG register initialization values
+PSGReset:
+        .byte   0x9f    /* set ch0 attenuation to max */
+        .byte   0xbf    /* set ch1 attenuation to max */
+        .byte   0xdf    /* set ch2 attenuation to max */
+        .byte   0xff    /* set ch3 attenuation to max */
+
+        .align  4
+
+        .include "font.s"
+
+        .align  4
+
+| short set_sr(short new_sr);
+| set SR, return previous SR
+| entry: arg = SR value
+| exit:  d0 = previous SR value
+set_sr:
+        moveq   #0,d0
+        move.w  sr,d0
+        move.l  4(sp),d1
+        move.w  d1,sr
+        rts
+
+| short get_pad(short pad);
+| return buttons for selected pad
+| entry: arg = pad index (0 or 1)
+| exit:  d0 = pad value (0 0 0 1 M X Y Z S A C B R L D U) or (0 0 0 0 0 0 0 0 S A C B R L D U)
+get_pad:
+        move.l  d2,-(sp)
+        move.l  8(sp),d0        /* first arg is pad number */
+        cmpi.w  #1,d0
+        bhi     no_pad
+        add.w   d0,d0
+        addi.l  #0xA10003,d0    /* pad control register */
+        movea.l d0,a0
+        bsr.b   get_input       /* - 0 s a 0 0 d u - 1 c b r l d u */
+        move.w  d0,d1
+        andi.w  #0x0C00,d0
+        bne.b   no_pad
+        bsr.b   get_input       /* - 0 s a 0 0 d u - 1 c b r l d u */
+        bsr.b   get_input       /* - 0 s a 0 0 0 0 - 1 c b m x y z */
+        move.w  d0,d2
+        bsr.b   get_input       /* - 0 s a 1 1 1 1 - 1 c b r l d u */
+        andi.w  #0x0F00,d0      /* 0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 */
+        cmpi.w  #0x0F00,d0
+        beq.b   common          /* six button pad */
+        move.w  #0x010F,d2      /* three button pad */
+common:
+        lsl.b   #4,d2           /* - 0 s a 0 0 0 0 m x y z 0 0 0 0 */
+        lsl.w   #4,d2           /* 0 0 0 0 m x y z 0 0 0 0 0 0 0 0 */
+        andi.w  #0x303F,d1      /* 0 0 s a 0 0 0 0 0 0 c b r l d u */
+        move.b  d1,d2           /* 0 0 0 0 m x y z 0 0 c b r l d u */
+        lsr.w   #6,d1           /* 0 0 0 0 0 0 0 0 s a 0 0 0 0 0 0 */
+        or.w    d1,d2           /* 0 0 0 0 m x y z s a c b r l d u */
+        eori.w  #0x1FFF,d2      /* 0 0 0 1 M X Y Z S A C B R L D U */
+        move.w  d2,d0
+        move.l  (sp)+,d2
+        rts
+
+| 3-button/6-button pad not found
+no_pad:
+        .ifdef  HAS_SMS_PAD
+        move.b  (a0),d0         /* - 1 c b r l d u */
+        andi.w  #0x003F,d0      /* 0 0 0 0 0 0 0 0 0 0 c b r l d u */
+        eori.w  #0x003F,d0      /* 0 0 0 0 0 0 0 0 0 0 C B R L D U */
+        .else
+        move.w  #0xF000,d0      /* SEGA_CTRL_NONE */
+        .endif
+        move.l  (sp)+,d2
+        rts
+
+| read single phase from controller
+get_input:
+        move.b  #0x00,(a0)
+        nop
+        nop
+        move.b  (a0),d0
+        move.b  #0x40,(a0)
+        lsl.w   #8,d0
+        move.b  (a0),d0
+        rts
+
+| void clear_b(void);
+| clear the name table for plane B
+clear_b:
+        moveq   #0,d0
+        lea     0xC00000,a0
+        move.w  #0x8F02,4(a0)           /* set INC to 2 */
+        move.l  #0x60000003,d1          /* VDP write VRAM at 0xE000 (scroll plane B) */
+        move.l  d1,4(a0)                /* write VRAM at plane B start */
+        move.w  #64*32-1,d1
+1:
+        move.w  d0,(a0)                 /* clear name pattern */
+        dbra    d1,1b
+        rts
+
+| void set_vram(int offset, int val);
+| store word to vram at offset
+| entry: first arg = offset in vram
+|        second arg = word to store
+set_vram:
+        lea     0xC00000,a1
+        move.w  #0x8F02,4(a1)           /* set INC to 2 */
+        move.l  4(sp),d1                /* vram offset */
+        lsl.l   #2,d1
+        lsr.w   #2,d1
+        swap    d1
+        ori.l   #0x40000000,d1          /* VDP write VRAM */
+        move.l  d1,4(a1)                /* write VRAM at offset*/
+        move.l  8(sp),d0                /* data word */
+        move.w  d0,(a1)                 /* set vram word */
+        rts
+
+| void next_vram(int val);
+| store word to vram at next offset
+| entry: first arg = word to store
+next_vram:
+        move.l  4(sp),d0                /* data word */
+        move.w  d0,0xC00000             /* set vram word */
+        rts
+
+| void copy_vram(int offset, void *src, int len);
+| store word to vram at offset
+| entry: first arg = offset in vram
+|        second arg = address of data to copy
+|        third arg = length of data to copy (in words)
+copy_vram:
+        lea     0xC00000,a1
+        move.w  #0x8F02,4(a1)           /* set INC to 2 */
+        move.l  4(sp),d1                /* vram offset */
+        lsl.l   #2,d1
+        lsr.w   #2,d1
+        swap    d1
+        ori.l   #0x40000000,d1          /* VDP write VRAM */
+        move.l  d1,4(a1)                /* write VRAM at offset*/
+        movea.l 8(sp),a0                /* source pointer */
+        move.l  12(sp),d0               /* length in words */
+        subq.w  #1,d0
+0:
+        move.w  (a0)+,(a1)              /* set vram word */
+        dbra    d0,0b
+        rts
+
+| void clear_a(void);
+| clear the name table for plane A
+clear_a:
+        moveq   #0,d0
+        lea     0xC00000,a0
+        move.w  #0x8F02,4(a0)           /* set INC to 2 */
+        move.l  #0x40000003,d1          /* VDP write VRAM at 0xC000 (scroll plane A) */
+        move.l  d1,4(a0)                /* write VRAM at plane A start */
+        move.w  #64*32-1,d1
+1:
+        move.w  d0,(a0)                 /* clear name pattern */
+        dbra    d1,1b
+        rts
+
+| void put_str(char *str, int color, int x, int y);
+| put string characters to the screen
+| entry: first arg = string address
+|        second arg = 0 for normal color font, N * 0x0200 for alternate color font (use CP bits for different colors)
+|        third arg = column at which to start printing
+|        fourth arg = row at which to start printing
+put_str:
+        movea.l 4(sp),a0                /* string pointer */
+        move.l  8(sp),d0                /* color palette */
+        lea     0xC00000,a1
+        move.w  #0x8F02,4(a1)           /* set INC to 2 */
+        move.l  16(sp),d1               /* y coord */
+        lsl.l   #6,d1
+        or.l    12(sp),d1               /* cursor y<<6 | x */
+        add.w   d1,d1                   /* pattern names are words */
+        swap    d1
+        ori.l   #0x40000003,d1          /* OR cursor with VDP write VRAM at 0xC000 (scroll plane A) */
+        move.l  d1,4(a1)                /* write VRAM at location of cursor in plane A */
+1:
+        move.b  (a0)+,d0
+        subi.b  #0x20,d0                /* font starts at space */
+        move.w  d0,(a1)                 /* set pattern name for character */
+        tst.b   (a0)
+        bne.b   1b
+        rts
+
+| void put_chr(char chr, int color, int x, int y);
+| put a character to the screen
+| entry: first arg = character
+|        second arg = 0 for normal color font, N * 0x0200 for alternate color font (use CP bits for different colors)
+|        third arg = column at which to start printing
+|        fourth arg = row at which to start printing
+put_chr:
+        movea.l 4(sp),a0                /* character */
+        move.l  8(sp),d0                /* color palette */
+        lea     0xC00000,a1
+        move.w  #0x8F02,4(a1)           /* set INC to 2 */
+        move.l  16(sp),d1               /* y coord */
+        lsl.l   #6,d1
+        or.l    12(sp),d1               /* cursor y<<6 | x */
+        add.w   d1,d1                   /* pattern names are words */
+        swap    d1
+        ori.l   #0x40000003,d1          /* OR cursor with VDP write VRAM at 0xC000 (scroll plane A) */
+        move.l  d1,4(a1)                /* write VRAM at location of cursor in plane A */
+
+        move.l  a0,d1
+        move.b  d1,d0
+        subi.b  #0x20,d0                /* font starts at space */
+        move.w  d0,(a1)                 /* set pattern name for character */
+        rts
+
+| void delay(int count);
+| wait count number of vertical blank periods - relies on vblank running
+| entry: arg = count
+delay:
+        move.l  4(sp),d1                /* count */
+        MD_VCOUNT
+        add.l   d0,d1                   /* add current vblank count */
+1:
+        MD_VCOUNT
+        cmp.l   d0,d1
+        bgt.b   1b
+        rts
+
+| void set_palette(short *pal, int start, int count)
+| copy count entries pointed to by pal into the palette starting at the index start
+| entry: pal = pointer to an array of words holding the colors
+|        start = index of the first color in the palette to set
+|        count = number of colors to copy
+set_palette:
+        movea.l 4(sp),a0                /* pal */
+        move.l  8(sp),d0                /* start */
+        move.l  12(sp),d1               /* count */
+        add.w   d0,d0                   /* start*2 */
+        swap    d0                      /* high word holds address */
+        ori.l   #0xC0000000,d0          /* write CRAM address (0 + index*2) */
+        subq.w  #1,d1                   /* for dbra */
+
+        lea     0xC00000,a1
+        move.w  #0x8F02,4(a1)           /* set INC to 2 */
+        move.l  d0,4(a1)                /* write CRAM */
+0:
+        move.w  (a0)+,(a1)              /* copy color to palette */
+        dbra    d1,0b
+        rts
+
+| void z80_busrequest(int flag)
+| set Z80 bus request
+| entry: flag = request/release
+z80_busrequest:
+        move.l  4(sp),d0                /* flag */
+        andi.w  #0x0100,d0
+        move.w  d0,0xA11100             /* set bus request */
+0:
+        move.w  0xA11100,d1
+        and.w   d0,d1
+        bne.b   0b
+        rts
+
+| void z80_reset(int flag)
+| set Z80 reset
+| entry: flag = assert/clear
+z80_reset:
+        move.l  4(sp),d0                /* flag */
+        andi.w  #0x0100,d0
+        move.w  d0,0xA11200             /* set reset */
+        rts
+
+| void z80_memclr(void *dst, int len)
+| clear Z80 sram
+| entry: dst = pointer to sram to clear
+|        len = length of memory to copy
+| note: you need to request the Z80 bus first
+z80_memclr:
+        movea.l 4(sp),a1                /* dst */
+        move.l  8(sp),d0                /* len */
+        subq.w  #1,d0
+        moveq   #0,d1
+0:
+        move.b  d1,(a1)+
+        dbra    d0,0b
+        rts
+
+| void z80_memcpy(void *dst, void *src, int len)
+| copy memory to Z80 sram
+| entry: dst = pointer to memory to copy to
+|        src = pointer to memory to copy from
+|        len = length of memory to copy
+| note: you need to request the Z80 bus first
+z80_memcpy:
+        movea.l 4(sp),a1                /* dst */
+        movea.l 8(sp),a0                /* src */
+        move.l  12(sp),d0               /* len */
+        subq.w  #1,d0
+0:
+        move.b  (a0)+,d1
+        move.b  d1,(a1)+
+        dbra    d0,0b
+        rts
+
+| void dma_screen(unsigned short *buffer, int wide);
+| dma buffer to background cmap entry
+dma_screen:
+        move.l  4(sp),d0                /* buffer */
+        move.l  8(sp),d1                /* wide flag */
+        movem.l d2-d7/a2-a6,-(sp)
+        move.w  #0x2700,sr              /* disallow interrupts */
+
+        /* VDP commands for DMA  */
+        move.l  #0x93E0948C,d2          /* DMALEN LO/HI = 0x8CE0 (161*224) */
+        tst.b   d1
+        beq.b   0f                      /* narrow screen */
+        /* wide screen */
+        move.l  #0x934094AD,d2          /* DMALEN LO/HI = 0xAD40 (198*224) */
+0:
+        move.l  #0x96009500,d3
+        lsr.l   #1,d0                   /* word bus */
+        move.b  d0,d3                   /* LOW address */
+        swap    d3
+        lsr.l   #8,d0
+        move.b  d0,d3                   /* MID address */
+        move.l  #0x81149700,d4
+        lsr.l   #8,d0
+        andi.w  #0x007F,d0
+        move.b  d0,d4                   /* HI address and dma mode */
+        swap    d4
+        move.l  #0xC0000080,d5          /* dest = write cram => start DMA */
+
+        /* clear palette */
+        moveq   #0,d0
+        lea     0xC00000,a2
+        lea     0xC00004,a3
+        moveq   #31,d1
+        move.l  #0xC0000000,(a3)        /* write CRAM address 0 */
+1:
+        move.l  d0,(a2)                 /* clear palette */
+        dbra    d1,1b
+
+        /* init VDP regs */
+        move.w  #0x8F00,(a3)            /*  clear INC register */
+        cmpi.l  #0x934094AD,d2
+        beq.b   dma_wide                /* wide screen display loop */
+        move.w  #0x8C00,(a3)            /* H32 mode, no lace, no shadow/hilite */
+        bra.w   dma_narrow              /* narrow screen display loop */
+
+        /* loop - turn on display and wait for vblank */
+dma_wide:
+        moveq   #0,d0
+        move.w  #0x8154,(a3)            /* turn on display (no VB int, V28 mode) */
+        move.l  #0x40000000,(a3)        /* write vram address 0 */
+1:
+        btst    #3,1(a3)
+        beq.b   1b                      /* wait for VB */
+2:
+        btst    #3,1(a3)
+        bne.b   2b                      /* wait for not VB */
+
+        move.l  d0,(a2)
+        move.l  d0,(a2)
+        move.l  d0,(a2)
+        move.l  d0,(a2)
+        move.l  d0,(a2)
+        move.l  d0,(a2)
+        move.w  d0,(a2)
+
+        nop
+        nop
+        nop
+        nop
+
+        /* Execute DMA */
+        nop
+        nop
+        move.l  d2,(a3)                 /* DMALEN LO/HI */
+        nop
+        nop
+        move.l  d3,(a3)                 /* DMA SRC LO/MID */
+        nop
+        nop
+        move.l  d4,(a3)                 /* DMA SRC HI/MODE, Turn off Display */
+        nop
+        nop
+        move.l  d5,(a3)                 /* start DMA */
+        /* CPU is halted until DMA is complete */
+
+        /* display finished, check request switch ram banks */
+        btst    #7,0xA1200F
+        beq.b   4f
+        nop
+        bset    #1,0xA12003             /* request switch ram banks */
+        nop
+3:
+        btst    #1,0xA12003
+        bne.b   3b                      /* wait for bank switch */
+4:
+        /* do other tasks here */
+        pea     0.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA12018
+
+        pea     1.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA1201A
+
+        move.l  0xA1201C,d0
+        addq.l  #1,d0
+        move.l  d0,0xA1201C             /* increment ticks */
+
+        move.w  0xA12000,d0
+        ori.w   #0x0100,d0
+        move.w  d0,0xA12000             /* generate level 2 int for CD */
+
+        moveq   #0x7F,d0
+        and.b   0xA1200F,d0
+        cmpi.b  #MD_CMD_DMA_SCREEN,d0
+        bne.b   exit_wide                /* no longer requesting DMA color display */
+        bra.w   dma_wide
+exit_wide:
+        bsr.w   md_init_hw
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+        /* loop - turn on display and wait for vblank */
+dma_narrow:
+        moveq   #0,d0
+        move.w  #0x8154,(a3)            /* turn on display (no VB int, V28 mode) */
+        move.l  #0x40000000,(a3)        /* write vram address 0 */
+1:
+        btst    #3,1(a3)
+        beq.b   1b                      /* wait for VB */
+2:
+        btst    #3,1(a3)
+        bne.b   2b                      /* wait for not VB */
+
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+        move.w  d0,(a2)
+
+        nop
+        nop
+        nop
+        nop
+
+        /* Execute DMA */
+        nop
+        nop
+        move.l  d2,(a3)                 /* DMALEN LO/HI */
+        nop
+        nop
+        move.l  d3,(a3)                 /* DMA SRC LO/MID */
+        nop
+        nop
+        move.l  d4,(a3)                 /* DMA SRC HI/MODE, Turn off Display */
+        nop
+        nop
+        move.l  d5,(a3)                 /* start DMA */
+        /* CPU is halted until DMA is complete */
+
+        /* display finished, check request switch ram banks */
+        btst    #7,0xA1200F
+        beq.b   4f
+        nop
+        bset    #1,0xA12003             /* request switch ram banks */
+        nop
+3:
+        btst    #1,0xA12003
+        bne.b   3b                      /* wait for bank switch */
+4:
+        /* do other tasks here */
+        pea     0.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA12018
+
+        pea     1.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA1201A
+
+        move.l  0xA1201C,d0
+        addq.l  #1,d0
+        move.l  d0,0xA1201C             /* increment ticks */
+
+        move.w  0xA12000,d0
+        ori.w   #0x0100,d0
+        move.w  d0,0xA12000             /* generate level 2 int for CD */
+
+        moveq   #0x7F,d0
+        and.b   0xA1200F,d0
+        cmpi.b  #MD_CMD_DMA_SCREEN,d0
+        bne.b   exit_narrow             /* no longer requesting DMA color display */
+        bra.w   dma_narrow
+exit_narrow:
+        bsr.w   md_init_hw
+        movem.l (sp)+,d2-d7/a2-a6
+        rts
+
+| int init_32x(void *data, int length);
+| init 32x, return status
+| entry: arg1 = 32X code/data (in word ram), arg2 = length of data
+| exit:  d0 = status
+init_32x:
+        move.l  0xA130EC,d0
+        cmpi.l  #0x4D415253,d0          /* 'MARS' */
+        beq.b   0f
+        moveq   #-2,d0                  /* no 32X detected */
+        rts
+0:
+        move.w  #0x2700,sr              /* disable ints */
+        lea     0xA15000,a0
+        move.b  #1,0x0101(a0)           /* activate 32X, assert SH2 RESET */
+
+        /* wait 10ms for 32X */
+        move.w  #19170,d1
+1:
+        dbra    d1,1b
+
+        moveq   #0,d0
+        move.l  d0,0x0120(a0)           /* clear COMM0 */
+        move.l  d0,0x0124(a0)           /* clear COMM4 */
+        move.b  #3,0x0101(a0)           /* deassert SH2 RESET */
+2:
+        bclr    #7,0x0100(a0)           /* get access to 32X VDP resources */
+        bne.b   2b
+        move.w  d0,0x0102(a0)           /* clear interrupt reg */
+        move.w  d0,0x0104(a0)           /* clear bank reg */
+        move.w  d0,0x0106(a0)           /* clear dreq control reg */
+        move.l  d0,0x0108(a0)           /* clear dreq src reg */
+        move.l  d0,0x010C(a0)           /* clear dreq dst reg */
+        move.w  d0,0x0110(a0)           /* clear dreq length reg */
+        move.w  d0,0x0130(a0)           /* clear pwm control reg */
+        move.w  d0,0x0132(a0)           /* clear pwm cycle reg */
+        move.w  d0,0x0138(a0)           /* clear pwm mono reg */
+        move.w  d0,0x0180(a0)           /* clear vdp mode reg */
+        move.w  d0,0x0182(a0)           /* clear vdp shift reg */
+3:
+        bclr    #0,0x018B(a0)           /* switch to frame 0 */
+        bne.b   3b
+        moveq   #-1,d1
+        lea     0x840000,a1             /* frame buffer */
+4:
+        move.w  d0,(a1)+                /* clear frame buffer */
+        dbra    d1,4b
+5:
+        bset    #0,0x018B(a0)           /* switch to frame 1 */
+        beq.b   5b
+        moveq   #-1,d1
+        lea     0x840000,a1             /* frame buffer */
+6:
+        move.w  d0,(a1)+                /* clear frame buffer */
+        dbra    d1,6b
+
+        moveq   #0x7F,d1
+        lea     0xA15200,a1             /* palette cram */
+7:
+        move.l  d0,(a1)+                /* clear palette */
+        dbra    d1,7b
+
+        move.l  0x0120(a0),d0           /* check Master SH2 */
+        cmpi.l  #0x53444552,d0          /* 'SDER' */
+        bne.b   8f
+        move.w  #0x2000,sr              /* enable ints */
+        moveq   #-3,d0                  /* sdram error */
+        rts
+8:
+        /* 32X initialized and ready, copy data/code to frame buffer */
+        movea.l 4(sp),a0                /* data/code */
+        move.l  8(sp),d0                /* length */
+        lea     0x840000,a1             /* frame buffer */
+9:
+        move.l  (a0)+,(a1)+
+        subq.l  #4,d0
+        bgt.b   9b
+
+        lea     0xA15000,a0
+        move.l  #0x5F43445F,0x0120(a0)  /* Master SH2 CD handshake '_CD_' */
+
+0:
+        move.l  0x0120(a0),d0
+        cmpi.l  #0x4D5F4F4B,d0          /* 'M_OK' */
+        bne.b   0b
+1:
+        move.l  0x0124(a0),d0
+        cmpi.l  #0x535F4F4B,d0          /* 'S_OK' */
+        bne.b   1b
+
+        moveq   #1,d7                   /* 32X initialized */
+        moveq   #0,d0
+        move.l  d0,0x0120(a0)           /* start Master SH2 (which should start Slave SH2) */
+
+        move.w  #0x2000,sr              /* enable ints */
+        rts
+
+| int get_comm32x(int offs, int len);
+| return communications register value of len at offset offs
+| entry: arg1 = offset from 0xA15120, arg2 = length of data (2 or 4 only)
+| exit:  d0 = communications register value or -1 (error)
+get_comm32x:
+        tst.b   d7
+        bne.b   0f
+        moveq   #-1,d0                  /* 32X not initialized */
+        rts
+0:
+        move.l  8(sp),d1                /* length */
+        cmpi.w  #2,d1
+        beq.b   2f
+        cmpi.w  #4,d1
+        beq.b   4f
+        moveq   #-1,d0                  /* bad parameter */
+        rts
+2:
+        move.l  4(sp),d1                /* offset */
+        moveq   #0,d0
+        lea     0xA15120,a0             /* COMM0 */
+        move.w  0(a0,d1.w),d0
+        rts
+4:
+        move.l  4(sp),d1                /* offset */
+        lea     0xA15120,a0             /* COMM0 */
+        move.l  0(a0,d1.w),d0
+        rts
+
+| int set_comm32x(int offs, int len, int val);
+| set communications register value of len at offset offs
+| entry: arg1 = offset from 0xA15120, arg2 = length of data (2 or 4 only), arg3 = value
+| exit:  d0 = 0 (okay) or -1 (error)
+set_comm32x:
+        tst.b   d7
+        bne.b   0f
+        moveq   #-1,d0                  /* 32X not initialized */
+        rts
+0:
+        moveq   #0,d0
+        move.l  8(sp),d1                /* length */
+        cmpi.w  #2,d1
+        beq.b   2f
+        cmpi.w  #4,d1
+        beq.b   4f
+        moveq   #-1,d0                  /* bad parameter */
+        rts
+2:
+        move.l  4(sp),d1                /* offset */
+        lea     0xA15120,a0             /* COMM0 */
+        move.w  14(sp),0(a0,d1.w)       /* val -> COMM0 + offset */
+        rts
+4:
+        move.l  4(sp),d1                /* offset */
+        lea     0xA15120,a0             /* COMM0 */
+        move.l  12(sp),0(a0,d1.w)       /* val -> COMM0 + offset */
+        rts
+
+| int dma_to_32x(short *src, int len);
+| DMA data from source to 32X
+| entry: arg1 = source pointer, arg2 = length of data (in words)
+| exit:  d0 = 0 (okay) or -1 (error) or -2 (DMA error)
+dma_to_32x:
+        tst.b   d7
+        bne.b   0f
+        moveq   #-1,d0                  /* 32X not initialized */
+        rts
+0:
+        lea     0xA15000,a1
+        move.b  #0x00,0x0107(a1)        /* clear 68S bit - stops SH DREQ */
+
+        movea.l 4(sp),a0                /* source address */
+        move.l  8(sp),d0                /* length in words */
+        addq.l  #3,d0
+        andi.w  #0xFFFC,d0              /* FIFO operates on units of four words */
+        move.w  d0,0x0110(a1)           /* SH DREQ Length Reg */
+        move.w  d0,0x0122(a1)           /* COMM2 = # words to dma */
+        lsr.l   #2,d0
+        subq.l  #1,d0                   /* for dbra */
+
+        move.b  #0x04,0x0107(a1)        /* set 68S bit - starts SH DREQ */
+        lea     0x0112(a1),a1
+1:
+        cmpi.w  #0x55AA,0xA15120        /* wait for SH2 to start DMA */
+        bne.b   1b
+2:
+        move.w  (a0)+,(a1)              /* FIFO = next word */
+        move.w  (a0)+,(a1)
+        move.w  (a0)+,(a1)
+        move.w  (a0)+,(a1)
+3:
+        btst    #7,0xA15107             /* check FIFO full flag */
+        bne.b   3b
+        dbra    d0,2b
+
+        btst    #2,0xA15107
+        bne.b   4f                      /* DMA not done? */
+        moveq   #0,d0
+        rts
+4:
+        moveq   #-2,d0
+        rts
+
+| int cpy_to_32x(short *src, int len);
+| copy data from source to 32X through COMM registers
+| entry: arg1 = source pointer, arg2 = length of data (in words)
+| exit:  d0 = 0 (okay) or -1 (error)
+cpy_to_32x:
+        tst.b   d7
+        bne.b   0f
+        moveq   #-1,d0                  /* 32X not initialized */
+        rts
+0:
+        movea.l 4(sp),a0                /* source pointer */
+        move.l  8(sp),d0                /* length */
+        subq.l  #1,d0                   /* for dbra */
+1:
+        move.w  (a0)+,0xA15122
+        move.w  #3,0xA15120             /* xfer next word */
+2:
+        cmpi.w  #1,0xA15120
+        bne.b   2b
+        dbra    d0,1b
+
+        move.w  #0xFFFF,0xA15120        /* xfer done */
+3:
+        cmpi.w  #0,0xA15120
+        bne.b   3b
+
+        moveq   #0,d0
+        rts
+
+| void md_memcpy(void *dst, void *src, int len)
+| copy memory
+| entry: dst = pointer to memory to copy to
+|        src = pointer to memory to copy from
+|        len = length of memory to copy
+md_memcpy:
+        movea.l 4(sp),a1                /* dst */
+        movea.l 8(sp),a0                /* src */
+        move.l  12(sp),d0               /* len */
+0:
+        move.b  (a0)+,d1
+        move.b  d1,(a1)+
+        subi.l  #1,d0
+        bgt.b   0b
+        moveq.l #0,d0
+        rts
+
+        .align  4
+
+| Vertical blank handler
+vblank_int:
+        movem.l d0-d1/a0-a1,-(sp)
+
+        pea     0.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA12018
+        tst.b   d7
+        beq.b   0f
+        move.w  d0,0xA15128
+0:
+        pea     1.w
+        bsr.w   get_pad
+        addq.l  #4,sp
+        move.w  d0,0xA1201A
+        tst.b   d7
+        beq.b   1f
+        move.w  d0,0xA1512A
+1:
+        move.l  0xA1201C,d0
+        addq.l  #1,d0
+        move.l  d0,0xA1201C             /* increment ticks */
+        tst.b   d7
+        beq.b   2f
+        move.l  d0,0xA1512C
+2:
+        move.w  0xA12000,d0
+        ori.w   #0x0100,d0
+        move.w  d0,0xA12000             /* generate level 2 int for CD */
+
+        movem.l (sp)+,d0-d1/a0-a1
+        rte
+
+        .align  4
+md_init_end:
+
+
+        .data
+
+        .align  4
+
+        .global global_vars
+global_vars:
+        .long   0
+
+iso_pvd_magic:
+        .asciz  "\1CD001\1"
+
+        .align  4
+
+        .text
diff --git a/demo/main.c b/demo/main.c
new file mode 100644
index 0000000..1a9a754
--- /dev/null
+++ b/demo/main.c
@@ -0,0 +1,342 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "hw_md.h"
+
+#define MAX_ENTRIES 256
+
+typedef struct
+{
+    int offset;
+    int length;
+    char flags;
+    char name[247];
+} entry_t;
+
+entry_t gDirTable[MAX_ENTRIES];
+
+short gCount = 0;
+short gFirst = 0;
+short gCurrent = 0;
+short gStage = 0;
+
+char *temp = (char *)0x0C0000;
+char *rom_start = (void*)0x400000;
+
+//----------------------------------------------------------------------
+
+int getCurrDir(void)
+{
+    int r = 0;
+    int i = 0;
+
+    while (!r)
+    {
+        r = next_dir_entry();
+        if (!r && memcmp(global_vars->DENTRY_NAME, ".", 2))
+        {
+            gDirTable[i].offset = global_vars->DENTRY_OFFSET;
+            gDirTable[i].length = global_vars->DENTRY_LENGTH;
+            gDirTable[i].flags = global_vars->DENTRY_FLAGS >> 8;
+            strcpy(gDirTable[i].name, global_vars->DENTRY_NAME);
+            i++;
+        }
+
+        if (r == ERR_NO_MORE_ENTRIES)
+            r = next_dir_sec();
+    }
+
+    return i;
+}
+
+void transfer(char *temp)
+{
+    int i, j;
+    int length;
+    int block, offset;
+
+    length = gDirTable[gCurrent].length;
+    offset = gDirTable[gCurrent].offset;
+
+    for (i = 0; i < length; )
+    {
+        int chunk = 0x20000;
+        int m68kchunk = 0x4000;
+
+        if (i + chunk > length)
+            chunk = length - i;
+
+        sprintf(temp, "Loading %08X-%08X\n", i, i+chunk);
+        switch_banks();
+        do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+
+        block = (i >> 11) + offset;
+        read_cd(block, (chunk + 0x7FF) >> 11, temp);
+#ifndef BUF_TEST
+        switch_banks();
+#endif
+        for (j = 0; j < chunk; ) {
+            if (j + m68kchunk > chunk)
+                m68kchunk = chunk - j;
+#ifndef BUF_TEST
+            do_md_cmd3(MD_CMD_CPY_MD, (intptr_t)rom_start+i+j, 0x200000+j, m68kchunk);
+#else
+            memcpy(buf+i+j, temp+j, m68kchunk);
+#endif
+            j += m68kchunk;
+        }
+
+        i += chunk;
+    }
+
+    strcpy(temp, "OK                                     ");
+    switch_banks();
+    do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+}
+
+void verify(char *temp)
+{
+    int i, j;
+    int mismatch = 0;
+    int length, offset, block;
+
+    length = gDirTable[gCurrent].length;
+    offset = gDirTable[gCurrent].offset;
+
+    for (i = 0; i < length; )
+    {
+        int chunk = 0x10000;
+        int m68kchunk = 0x4000;
+        volatile char *temp2 = temp + 0x10000;
+
+        if (i + chunk > length)
+            chunk = length - i;
+
+        sprintf(temp, "Verifying %07X-%07X\n", i, i+chunk);
+        switch_banks();
+        do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+
+        block = (i >> 11) + offset;
+        read_cd(block, (chunk + 0x7FF) >> 11, temp);
+
+        switch_banks();
+
+        for (j = 0; j < chunk; ) {
+            if (j + m68kchunk > chunk)
+                m68kchunk = chunk - j;
+
+            do_md_cmd3(MD_CMD_CPY_MD, 0x200000+0x10000+j, (intptr_t)rom_start+i+j, m68kchunk);
+
+            j += m68kchunk;
+        }
+
+        switch_banks();
+
+        for (j = 0; j < chunk; j++)
+        {
+            if (temp[j] != temp2[j])
+            {
+                int c1 = temp[j]&0xff;
+                int c2 = temp2[j]&0xff;
+                mismatch = 1;
+                sprintf(temp, "Mismatch %07X %02X/%02X  \n", i+j, c1, c2);
+                switch_banks();
+                do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+                break;
+            }
+        }
+
+        if (mismatch)
+            break;
+
+        i += chunk;
+    }
+
+    if (!mismatch)
+    {
+        strcpy(temp, "OK                                     ");
+        switch_banks();
+        do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+    }
+}
+
+int main(void)
+{
+    int i, j;
+    unsigned short buttons, changed, previous = 0;
+
+    strcpy(temp, "ROM Player");
+    switch_banks();
+    do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_WHITE, 15, 1);
+
+    init_cd(); // init CD
+    set_cwd("/"); // set current directory to root
+    gCount = getCurrDir();
+
+    gStage = 0;
+
+    while (1)
+    {
+
+        if (gStage == 0)
+        {
+ 
+            char *p = temp;
+
+            // update display with directory entries
+            memset(p, 0, 20*64*2);
+            if (gCount)
+                for (i = 0; i < 20; i++)
+                {
+                    if ((gFirst + i) >= gCount)
+                        break;
+
+                    p = &temp[i*64*2 + 2]; // left justified
+                    if (gDirTable[gFirst + i].flags & 2)
+                    {
+                        // directory
+                        *p++ = ((gFirst + i) == gCurrent) ? TEXT_WHITE >> 8 : TEXT_GREEN >> 8;
+                        *p++ = '[' - 0x20;
+                        for (j = 0; j < 36; j++)
+                        {
+                            if (gDirTable[gFirst + i].name[j] == '\0')
+                                break;
+                            *p++ = ((gFirst + i) == gCurrent) ? TEXT_WHITE >> 8 : TEXT_GREEN >> 8;
+                            *p++ = gDirTable[gFirst + i].name[j] - 0x20;
+                        }
+                        *p++ = ((gFirst + i) == gCurrent) ? TEXT_WHITE >> 8 : TEXT_GREEN >> 8;
+                        *p++ = ']' - 0x20;
+                    }
+                    else
+                    {
+                        for (j = 0; j < 38; j++)
+                        {
+                            if (gDirTable[gFirst + i].name[j] == '\0')
+                                break;
+                            *p++ = ((gFirst + i) == gCurrent) ? TEXT_WHITE >> 8 : TEXT_GREEN >> 8;
+                            *p++ = gDirTable[gFirst + i].name[j] - 0x20;
+                        }
+                    }
+                }
+            switch_banks();
+            sub_delay(1); // wait until vblank to update vram
+            i = do_md_cmd3(MD_CMD_COPY_VRAM, 0xC000 + 3*64*2, 0x200000, 20*64); // update plane A name table (20 lines of text)
+            if (i < 0)
+            {
+                if (i == -1)
+                    strcpy(temp, "unknown command");
+                else if (i == -2)
+                    strcpy(temp, "wait cmd done timeout");
+                else if (i == -3)
+                    strcpy(temp, "wait cmd ack timeout");
+                else
+                    strcpy(temp, "unknown error");
+                switch_banks();
+                do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_RED, 1, 24);
+                sub_delay(120);
+                strcpy(temp, "                                       ");
+                switch_banks();
+                do_md_cmd4(MD_CMD_PUT_STR, 0x200000, TEXT_GREEN, 1, 24);
+            }
+
+            sub_delay(7);
+
+            gStage = 1;
+
+        } 
+        else if (gStage == 1)
+        {
+
+            buttons = GET_PAD(0);
+
+            changed = (buttons & SEGA_CTRL_BUTTONS) ^ previous;
+
+            if (buttons & SEGA_CTRL_DOWN)
+            {
+                // DOWN pressed
+                gCurrent++;
+                if ((gCurrent - gFirst) >= 20)
+                    gFirst = gCurrent;
+
+                if (gCurrent >= gCount)
+                    gFirst = gCurrent = 0; // wrap around to first entry
+
+                gStage = 0;
+
+            }
+
+            if (buttons & SEGA_CTRL_UP)
+            {
+
+                // UP pressed
+                gCurrent--;
+                if (gCurrent < gFirst)
+                {
+                    gFirst = gCurrent - 19;
+                    if (gFirst < 0)
+                        gFirst = 0;
+                }
+
+                if (gCurrent < 0)
+                {
+                    gCurrent = gCount - 1; // wrap around to last entry
+                    gFirst = gCurrent - 19;
+                    if (gFirst < 0)
+                        gFirst = 0;
+                }
+
+                gStage = 0;
+
+            }
+
+            if (!changed)
+                continue; // no change in buttons
+            previous = buttons & SEGA_CTRL_BUTTONS;
+
+            if (changed & SEGA_CTRL_A)
+            {
+                if (!(buttons & SEGA_CTRL_A))
+                {
+                    // A just released
+                    if (gDirTable[gCurrent].flags & 2)
+                    {
+                        // directory
+                        global_vars->CWD_OFFSET = gDirTable[gCurrent].offset;
+                        global_vars->CWD_LENGTH = gDirTable[gCurrent].length;
+                        global_vars->CURR_OFFSET = -1;
+                        first_dir_sec();
+                        gCount = getCurrDir();
+                        gFirst = gCurrent = 0;
+                        gStage = 0;
+                    }
+                    else
+                    {
+                        transfer(temp);
+                    }
+                }
+            }
+
+            if (changed & SEGA_CTRL_B)
+            {
+                if (!(buttons & SEGA_CTRL_B))
+                {
+                    // B just released
+                    if (gDirTable[gCurrent].flags & 2)
+                    {
+                        // directory
+                    }
+                    else
+                    {
+                        verify(temp);
+                    }
+                }
+            }
+        }
+    
+    }
+
+    return 0;
+}
+
diff --git a/demo/temp.bin b/demo/temp.bin
new file mode 100644
index 0000000..5f253b1
Binary files /dev/null and b/demo/temp.bin differ