tobiasvl / lua-8080

Intel 8080 emulator core, written in Lua

lua-8080

An Intel 8080 emulator core written in Lua.

Requirements

Either the bit32 or BitOp module for bitwise operators.

Usage

This emulator core is modular, like the early microcomputers. It should be able to emulate most 8080-based computers, but you need to "wire it up" yourself, just like the old days.

See main.lua for an example of how to use it in your own programs.

You can also look at these emulators that use this core:

• Moon Invaders (Space Invaders emulator)
• ALTAÏR (Altair 8800 emulator)

Tests

You can download one of the many Intel 8080 test suites and run them with the main.lua script.

Currently, it passes these tests:

• 8080PRE.COM: Preliminary test for 8080/8085 CPU Exerciser by Ian Bartholomew and Frank Cringles
• 8080EXER.COM: 8080/8085 CPU Exerciser by Ian Bartholomew and Frank Cringles
• TST8080.COM: 8080/8085 CPU Diagnostic, version 1.0, by Microcosm Associates
• CPUTEST.COM: 8080/Z80 CPU Diagnostic II, by SuperSoft Associates

lua-8080's Issues

Optimize bus

Turns out my bus implementation is inefficient. Not a good place for a bottleneck...

I still need it to be modular, but the current way I do it, ie. with a memory_map table where the key is a table with start address and length, isn't good – even though the memory map is usually small, pairs is un-JIT-able.

Optimize with local variables

Make local variables instead of elements of self, especially in instructions.lua.

Pass CPUTEST.COM

Rename to moon-8080

To coincide with the imminent (lol) release of moon6800

Add LDoc comments and generate documentation

Make into a Lua Rock

Disassembler misses a DAA

No idea what causes this (I can't reproduce it in a smaller program), but when running 8080EXM.COM the DAA at cycle 86712065 is mistakenly disassembled as a NOP. (It's still executed correctly.)

To reproduce:

tvl@rocinante:~/src/lua-8080 $ luajit main.lua 8080EXM.COM debug
tvl@rocinante:~/src/lua-8080 $ grep -C 2 86712065 debug.log
PC: 0D54, AF: 9A06, BC: 9079, DE: 8D5B, HL: 299D, SP: 0111, CYC: 86712044 (F9 2A A2 0D) - SPHL
PC: 0D55, AF: 9A06, BC: 9079, DE: 8D5B, HL: 299D, SP: 299D, CYC: 86712049 (2A A2 0D 27) - LHLD #A20D
PC: 0D58, AF: 9A06, BC: 9079, DE: 8D5B, HL: A559, SP: 299D, CYC: 86712065 (27 00 00 00) - NOP
PC: 0D59, AF: 0017, BC: 9079, DE: 8D5B, HL: A559, SP: 299D, CYC: 86712069 (00 00 00 22) - NOP
PC: 0D5A, AF: 0017, BC: 9079, DE: 8D5B, HL: A559, SP: 299D, CYC: 86712073 (00 00 22 A2) - NOP

Pass 8080EXER.COM

dad <b,d,h,sp>................  PASS! crc is:14474ba6
aluop nn......................  PASS! crc is:9e922f9e
aluop <b,c,d,e,h,l,m,a>.......  PASS! crc is:cf762c86
<daa,cma,stc,cmc>.............  ERROR **** crc expected:bb3f030c found:12da49a1
<inr,dcr> a...................  PASS! crc is:adb6460e
<inr,dcr> b...................  PASS! crc is:83ed1345
<inx,dcx> b...................  PASS! crc is:f79287cd
<inr,dcr> c...................  PASS! crc is:e5f6721b
<inr,dcr> d...................  PASS! crc is:15b5579a
<inx,dcx> d...................  PASS! crc is:7f4e2501
<inr,dcr> e...................  PASS! crc is:cf2ab396
<inr,dcr> h...................  PASS! crc is:12b2952c
<inx,dcx> h...................  PASS! crc is:9f2b23c0
<inr,dcr> l...................  PASS! crc is:ff57d356
<inr,dcr> m...................  PASS! crc is:92e963bd
<inx,dcx> sp..................  PASS! crc is:d5702fab
lhld nnnn.....................  PASS! crc is:a9c3d5cb
shld nnnn.....................  PASS! crc is:e8864f26
lxi <b,d,h,sp>,nnnn...........  PASS! crc is:fcf46e12
ldax <b,d>....................  PASS! crc is:2b821d5f
mvi <b,c,d,e,h,l,m,a>,nn......  PASS! crc is:eaa72044
mov <bcdehla>,<bcdehla>.......  PASS! crc is:10b58cee
sta nnnn / lda nnnn...........  PASS! crc is:ed57af72
<rlc,rrc,ral,rar>.............  PASS! crc is:e0d89235
stax <b,d>....................  PASS! crc is:2b0471e9
Tests complete
real    51m46.682s
user    51m31.391s
sys     0m0.531s

Really need to optimize to debug this test...