The Jolly Good Z80

The Jolly Good Z80 is a fast and accurate Z80 emulator written in C11.

This emulator passes both the ZEXDOC and ZEXALL Z80 instruction tests. It has also been verified correct against VisualZ80, and is known to run the entire ColecoVision, SG-1000, Master System, Game Gear, and Neo Geo libraries. Additionally, it has been successfully integrated into Mega Drive/Genesis emulators with unknown (but likely high or perfect) compatibility.

Licensing

This project is licensed under the MIT license, except the files in roms which are provided for convenient testing of the Z80 core implementation. These files' authors and licenses may be seen in the source files.

This emulator is a fork of superzazu/z80.

This emulator has been ported to Rust: kirjavascript/z80.

Tests

You can run the tests by running make && ./z80_tests, which outputs:

*** TEST: roms/prelim.com
Preliminary tests complete
*** 899 instructions executed on 8721 cycles (expected=8721, diff=0)

*** TEST: roms/zexdoc.cim
Z80doc instruction exerciser
<adc,sbc> hl,<bc,de,hl,sp>....  OK
add hl,<bc,de,hl,sp>..........  OK
add ix,<bc,de,ix,sp>..........  OK
add iy,<bc,de,iy,sp>..........  OK
aluop a,nn....................  OK
aluop a,<b,c,d,e,h,l,(hl),a>..  OK
aluop a,<ixh,ixl,iyh,iyl>.....  OK
aluop a,(<ix,iy>+1)...........  OK
bit n,(<ix,iy>+1).............  OK
bit n,<b,c,d,e,h,l,(hl),a>....  OK
cpd<r>........................  OK
cpi<r>........................  OK
<daa,cpl,scf,ccf>.............  OK
<inc,dec> a...................  OK
<inc,dec> b...................  OK
<inc,dec> bc..................  OK
<inc,dec> c...................  OK
<inc,dec> d...................  OK
<inc,dec> de..................  OK
<inc,dec> e...................  OK
<inc,dec> h...................  OK
<inc,dec> hl..................  OK
<inc,dec> ix..................  OK
<inc,dec> iy..................  OK
<inc,dec> l...................  OK
<inc,dec> (hl)................  OK
<inc,dec> sp..................  OK
<inc,dec> (<ix,iy>+1).........  OK
<inc,dec> ixh.................  OK
<inc,dec> ixl.................  OK
<inc,dec> iyh.................  OK
<inc,dec> iyl.................  OK
ld <bc,de>,(nnnn).............  OK
ld hl,(nnnn)..................  OK
ld sp,(nnnn)..................  OK
ld <ix,iy>,(nnnn).............  OK
ld (nnnn),<bc,de>.............  OK
ld (nnnn),hl..................  OK
ld (nnnn),sp..................  OK
ld (nnnn),<ix,iy>.............  OK
ld <bc,de,hl,sp>,nnnn.........  OK
ld <ix,iy>,nnnn...............  OK
ld a,<(bc),(de)>..............  OK
ld <b,c,d,e,h,l,(hl),a>,nn....  OK
ld (<ix,iy>+1),nn.............  OK
ld <b,c,d,e>,(<ix,iy>+1)......  OK
ld <h,l>,(<ix,iy>+1)..........  OK
ld a,(<ix,iy>+1)..............  OK
ld <ixh,ixl,iyh,iyl>,nn.......  OK
ld <bcdehla>,<bcdehla>........  OK
ld <bcdexya>,<bcdexya>........  OK
ld a,(nnnn) / ld (nnnn),a.....  OK
ldd<r> (1)....................  OK
ldd<r> (2)....................  OK
ldi<r> (1)....................  OK
ldi<r> (2)....................  OK
neg...........................  OK
<rrd,rld>.....................  OK
<rlca,rrca,rla,rra>...........  OK
shf/rot (<ix,iy>+1)...........  OK
shf/rot <b,c,d,e,h,l,(hl),a>..  OK
<set,res> n,<bcdehl(hl)a>.....  OK
<set,res> n,(<ix,iy>+1).......  OK
ld (<ix,iy>+1),<b,c,d,e>......  OK
ld (<ix,iy>+1),<h,l>..........  OK
ld (<ix,iy>+1),a..............  OK
ld (<bc,de>),a................  OK
Tests complete
*** 5764169747 instructions executed on 46734978649 cycles (expected=46734978649, diff=0)

*** TEST: roms/zexall.cim
Z80all instruction exerciser
<adc,sbc> hl,<bc,de,hl,sp>....  OK
add hl,<bc,de,hl,sp>..........  OK
add ix,<bc,de,ix,sp>..........  OK
add iy,<bc,de,iy,sp>..........  OK
aluop a,nn....................  OK
aluop a,<b,c,d,e,h,l,(hl),a>..  OK
aluop a,<ixh,ixl,iyh,iyl>.....  OK
aluop a,(<ix,iy>+1)...........  OK
bit n,(<ix,iy>+1).............  OK
bit n,<b,c,d,e,h,l,(hl),a>....  OK
cpd<r>........................  OK
cpi<r>........................  OK
<daa,cpl,scf,ccf>.............  OK
<inc,dec> a...................  OK
<inc,dec> b...................  OK
<inc,dec> bc..................  OK
<inc,dec> c...................  OK
<inc,dec> d...................  OK
<inc,dec> de..................  OK
<inc,dec> e...................  OK
<inc,dec> h...................  OK
<inc,dec> hl..................  OK
<inc,dec> ix..................  OK
<inc,dec> iy..................  OK
<inc,dec> l...................  OK
<inc,dec> (hl)................  OK
<inc,dec> sp..................  OK
<inc,dec> (<ix,iy>+1).........  OK
<inc,dec> ixh.................  OK
<inc,dec> ixl.................  OK
<inc,dec> iyh.................  OK
<inc,dec> iyl.................  OK
ld <bc,de>,(nnnn).............  OK
ld hl,(nnnn)..................  OK
ld sp,(nnnn)..................  OK
ld <ix,iy>,(nnnn).............  OK
ld (nnnn),<bc,de>.............  OK
ld (nnnn),hl..................  OK
ld (nnnn),sp..................  OK
ld (nnnn),<ix,iy>.............  OK
ld <bc,de,hl,sp>,nnnn.........  OK
ld <ix,iy>,nnnn...............  OK
ld a,<(bc),(de)>..............  OK
ld <b,c,d,e,h,l,(hl),a>,nn....  OK
ld (<ix,iy>+1),nn.............  OK
ld <b,c,d,e>,(<ix,iy>+1)......  OK
ld <h,l>,(<ix,iy>+1)..........  OK
ld a,(<ix,iy>+1)..............  OK
ld <ixh,ixl,iyh,iyl>,nn.......  OK
ld <bcdehla>,<bcdehla>........  OK
ld <bcdexya>,<bcdexya>........  OK
ld a,(nnnn) / ld (nnnn),a.....  OK
ldd<r> (1)....................  OK
ldd<r> (2)....................  OK
ldi<r> (1)....................  OK
ldi<r> (2)....................  OK
neg...........................  OK
<rrd,rld>.....................  OK
<rlca,rrca,rla,rra>...........  OK
shf/rot (<ix,iy>+1)...........  OK
shf/rot <b,c,d,e,h,l,(hl),a>..  OK
<set,res> n,<bcdehl(hl)a>.....  OK
<set,res> n,(<ix,iy>+1).......  OK
ld (<ix,iy>+1),<b,c,d,e>......  OK
ld (<ix,iy>+1),<h,l>..........  OK
ld (<ix,iy>+1),a..............  OK
ld (<bc,de>),a................  OK
Tests complete
*** 5764169747 instructions executed on 46734978649 cycles (expected=46734978649, diff=0)

Resources

• Z80 CPU User Manual
• Z80 instruction set (+ timings)
• Z80 timings
• Decoding Z80 Opcodes
• anotherlin/z80emu