SpaceInvaders

Space Invaders emulator written in C

Logging lib used can be found here

• https://github.com/rxi/

Source to look at for reference

• https://altairclone.com/downloads/manuals/8080%20Programmers%20Manual.pdf
• http://www.emulator101.com/reference/8080-by-opcode.html
• https://pastraiser.com/cpu/i8080/i8080_opcodes.html

Following this order of emulators

• Chip 8
• Space Invaders
• Pacman
• Gameboy
• GBC
• Sega Master System
• Sega Genesis

Intel 8080 Test

https://altairclone.com/downloads/cpu_tests/ You can find some Intel 8080 CPU tests on this website. These can be run with no OS, just a minimal support framework described below:

These binaries should be loaded to memory starting at 0x0100, and at startup, your CPU should jump to 0x0100. You should also put two handlers at addresses 0x0000 and 0x0005:

The handler at 0x0000 signals the end of the test run.v

The handler at 0x0005 is used to communicate the values of the registers C, D and E 
with the outside world. Register C selects from multiple functions:
    C = 0x02 signals printing the value of register E as an ASCII value
    C = 0x09 signals printing the value of memory pointed to by DE until a '$' character
    is encountered

The easiest is to put an OUT instruction at 0x0000 onwards, and an IN followed by a RET at 0x0005 onwards, and then set your emulator to do the right thing on port writes / reads.

I have implemented this protocol in a testbench for an FPGA Intel 8080 implementation inspired by a software emulator test suite; both of these could be useful references for you in implementing the scaffolding necessary to run these CPU tests without any complicated OS, or even any computer, around your CPU.

ALMOST PASSING AL EXER8080 TESTS

Issue #1: Always Clear Bit 5 and Bit 3, and Set Bit 1 for POP PSW instruction.

Issue #2: Auxillary Carry Flag (AC) value calculation incorrect for subtraction.

Issue #3: ANA and ANI set Auxillary Carry Flag (AC) to the OR'ing of bits 3 of the two operands.

Issue #4: XRA, XRI, ORA, ORI clear Auxillary Carry Flag (AC).

Issue #5: Auxillary Carry Flag (AC) value calculation incorrect for addition.

Issue #6: The prior Carry Flag (CY) value needs to be taken into account for SBB and SBI subtraction with borrow instuctions.

Issue #7: The prior Carry Flag (CY) value needs to be taken into account for ADC and ACI addition with carry instructions.

Issue #8: The DAA adjustment can also cause the Carry Flag (CY) to be set during the addition to the 4 low order bits.

Issue #9: The DAA adjustment can cause the Carry Flag (CY) to be set, but not to be clear if it was already set.