CPU Comparision with Z80 - Revision history

Nitro2k01 at 02:22, 5 April 2020

2020-04-05T02:22:48Z

Nitro2k01 at 02:22, 5 April 2020

2020-04-05T02:22:25Z

PinoBatch: Remaining changes, not included before to reduce diff desync

2018-05-05T22:15:35Z

Remaining changes, not included before to reduce diff desync

PinoBatch: 1/1: IN/OUT, EX *,HL, and JP PE/PO/P/M are differences compared all the way back to 8080. Also fix some grammar, usage, and mechanics that

2018-05-05T22:10:21Z

1/1: IN/OUT, EX *,HL, and JP PE/PO/P/M are differences compared all the way back to 8080. Also fix some grammar, usage, and mechanics that

Xzakox at 12:59, 28 June 2009

2009-06-28T12:59:42Z

Xzakox: New page: ===Comparision with 8080=== Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also...

2009-06-28T10:58:19Z

New page: ===Comparision with 8080=== Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also...

New page

===Comparision with 8080===
Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also, all known gameboy assemblers using the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.

===Comparision with Z80===
Any DD-, ED-, and FD-prefixed instructions are missing, that means no IX-, IY-registers, no block commands, and some other missing commands.
All exchange instructions have been removed (including total absence of second register set), 16bit memory accesses are mostly missing, and 16bit arithmetic functions are heavily cut-down.
The gameboy has no IN/OUT instructions, instead I/O ports are accessed directly by normal LD instructions, or by special LD (FF00+n) opcodes.
The sign and parity/overflow flags have been removed.
The gameboy operates approximately as fast as a 4MHz Z80 (8MHz in CGB double speed mode), execution time of all instructions has been rounded up to a multiple of 4 cycles though.

===Moved, Removed, and Added Opcodes===

Opcode Z80 GMB
---------------------------------------
08 EX AF,AF LD (nn),SP
10 DJNZ PC+dd STOP
22 LD (nn),HL LDI (HL),A
2A LD HL,(nn) LDI A,(HL)
32 LD (nn),A LDD (HL),A
3A LD A,(nn) LDD A,(HL)
D3 OUT (n),A -
D9 EXX RETI
DB IN A,(n) -
DD <IX> -
E0 RET PO LD (FF00+n),A
E2 JP PO,nn LD (FF00+C),A
E3 EX (SP),HL -
E4 CALL P0,nn -
E8 RET PE ADD SP,dd
EA JP PE,nn LD (nn),A
EB EX DE,HL -
EC CALL PE,nn -
ED <pref> -
F0 RET P LD A,(FF00+n)
F2 JP P,nn LD A,(FF00+C)
F4 CALL P,nn -
F8 RET M LD HL,SP+dd
FA JP M,nn LD A,(nn)
FC CALL M,nn -
FD <IY> -
CB3X SLL r/(HL) SWAP r/(HL)

== Note: ==
The unused (-) opcodes will lock-up the gameboy CPU when used.

@@ Line 1: / Line 1: @@
-{{Pandocs|cpucomparison-with-z80}}
+{{Pandocs|comparison-with-z80}}
 ===Comparison with 8080===
 The Game Boy CPU has a bit more in common with an older Intel 8080 CPU than the more powerful Zilog Z80 CPU. It is missing a handful of 8080 instructions but does support JR and almost all CB-prefixed instructions. Also, all known Game Boy assemblers use the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.

@@ Line 1: / Line 1: @@
-{{Pandocs|cpucomparisionwithz80}}
+{{Pandocs|cpucomparison-with-z80}}
 ===Comparison with 8080===
 The Game Boy CPU has a bit more in common with an older Intel 8080 CPU than the more powerful Zilog Z80 CPU. It is missing a handful of 8080 instructions but does support JR and almost all CB-prefixed instructions. Also, all known Game Boy assemblers use the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.

@@ Line 1: / Line 1: @@
 {{Pandocs|cpucomparisionwithz80}}
 ===Comparison with 8080===
-The Game Boy CPU has a bit more in common with an older Intel 8080 CPU than the more powerful Zilog Z80 CPU. It is missing a handful of 8080 instructions but does support almost all CB-prefixed instructions. Also, all known Game Boy assemblers use the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.
+The Game Boy CPU has a bit more in common with an older Intel 8080 CPU than the more powerful Zilog Z80 CPU. It is missing a handful of 8080 instructions but does support JR and almost all CB-prefixed instructions. Also, all known Game Boy assemblers use the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.
 Unlike the 8080 and Z80, the Game Boy has no dedicated I/O bus and no IN/OUT opcodes. Instead, I/O ports are accessed directly by normal LD instructions, or by new LD (FF00+n) opcodes.
@@ Line 7: / Line 7: @@
 The sign and parity/overflow flags have been removed, as have the 12 RET, CALL, and JP instructions conditioned on them. So have EX (SP),HL (XTHL) and EX DE,HL (XCHG).
-===Comparision with Z80===
+===Comparison with Z80===
-All DD- and FD-prefixed instructions are missing. That means no IX- or IY-registers.
-−
 In addition to the removed 8080 instructions, the other exchange instructions have been removed (including total absence of second register set).
-All ED-prefixed instructions are missing. That means 16bit memory accesses are mostly missing, 16bit arithmetic functions are heavily cut-down, no block commands, and some other missing commands. IN/OUT (C) are replaced with new LD ($FF00+C) opcodes.
+All DD- and FD-prefixed instructions are missing. That means no IX- or IY-registers.
 The Game Boy operates approximately as fast as a 4 MHz Z80 (8 MHz in CGB double speed mode), with execution time of all instructions having been rounded up to a multiple of 4 cycles.

← Older revision		Revision as of 12:59, 28 June 2009
Line 1:		Line 1:
		+	{{Pandocs\|cpucomparisionwithz80}}
	===Comparision with 8080===		===Comparision with 8080===
	Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also, all known gameboy assemblers using the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.		Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also, all known gameboy assemblers using the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.

@@ Line 1: / Line 1: @@
 {{Pandocs|cpucomparisionwithz80}}
-===Comparision with 8080===
+===Comparison with 8080===
-Basically, the gameboy CPU works more like an older 8080 CPU rather than like a more powerful Z80 CPU. It is, however, supporting CB-prefixed instructions. Also, all known gameboy assemblers using the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.
+The Game Boy CPU has a bit more in common with an older Intel 8080 CPU than the more powerful Zilog Z80 CPU. It is missing a handful of 8080 instructions but does support almost all CB-prefixed instructions. Also, all known Game Boy assemblers use the more obvious Z80-style syntax, rather than the chaotic 8080-style syntax.
 ===Comparision with Z80===
-Any DD-, ED-, and FD-prefixed instructions are missing, that means no IX-, IY-registers, no block commands, and some other missing commands.
+All DD- and FD-prefixed instructions are missing. That means no IX- or IY-registers.
-All exchange instructions have been removed (including total absence of second register set), 16bit memory accesses are mostly missing, and 16bit arithmetic functions are heavily cut-down.
-The gameboy has no IN/OUT instructions, instead I/O ports are accessed directly by normal LD instructions, or by special LD (FF00+n) opcodes.
+In addition to the removed 8080 instructions, the other exchange instructions have been removed (including total absence of second register set).
-The sign and parity/overflow flags have been removed.
-The gameboy operates approximately as fast as a 4MHz Z80 (8MHz in CGB double speed mode), execution time of all instructions has been rounded up to a multiple of 4 cycles though.
+All ED-prefixed instructions are missing. That means 16bit memory accesses are mostly missing, 16bit arithmetic functions are heavily cut-down, no block commands, and some other missing commands. IN/OUT (C) are replaced with new LD ($FF00+C) opcodes.
 ===Moved, Removed, and Added Opcodes===
@@ Line 42: / Line 48: @@
    CB3X    SLL  r/(HL)     SWAP r/(HL)
+Note: The unused (-) opcodes will lock up the Game Boy CPU when used.
-== Note: ==
-The unused (-) opcodes will lock-up the gameboy CPU when used.