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Changed: 3c3
Someon changed separate z80 CPU to integrated 6502 CPU. Now, I think that it is a z80 CPU, same as on Game Boy, different to SNES (which was 6502!). I don't care to speculate as to whether the CPU is on the same die as the ARM or not, but if I had to guess then on the same die seems very plausible. Will try and find some evidence. --drj Definitely Z80.
Damian Yerrick summarized old talk:

Changed: 5,6c5,9


According to official programming manual, "integral 8 bit CISC CPU for compatibility". In context it seemed to say that the CPU was integrated, and the ARM in it *is* a custom chip for nintendo, but now it implies to me its integrated into the "system". I swear I read this somewhere else too, but for right now its too ambiguous so I'll take it out. (the block diagram doesn't show it as integrated either).
Game Boy products contain a "integral 8 bit CISC CPU for compatibility," namely the same Sharp Z80-like CPU (not an official Zilog design) used in the Game Boy Color.
It runs at 4 MHz when playing GB titles and 8 MHz when playing GBC titles.
GBA does not contain a 6502 processor (as somebody changed); Z80 instructions are completely incompatible with MOS Technologies 6502 instructions.
Z80 and 6502 are not members of the same family; their instruction sets and timings aren't even close.
We're not sure whether the ARM7TDMI and the GBZ80 are on the same die.

Removed: 8d10
BTW, I was thinking original GB when I said 6502, however, aren't they about the same pinout? technically the GBC CPU is a z80 "clone", of which 6502 and LR35902 are family members? I seem to recall certain variant instructions being unsupported in the GB because of this. (maybe this topic can flesh out the GBC entry.

Changed: 10c12,14
Game Boy and Game Boy Color use a Z80 clone. Few people care about it being a clone. Anyway most decent clones are in fact licensed designs from Zilog. 4MHz for the Game Boy, 8 MHz for the Game Boy Color (running at 4 MHz when playing grey Game Boy carts).
Just for reference, the 6502 processor (with BCD mode removed) was used in NES; the Super NES used a [WDC 65C816]?.
However, the existence of the PocketNES? emulator for GBA proves that NES emulation (and thus 6502 emulation) on ARM is far from impossible.
--Damian Yerrick

Changed: 12c16
The 6502 is a different beast altogether. It is an 8 bit CPU, but totally incompatible with the z80. --drj



I might put out my photos of it.
Damian Yerrick summarized old talk:

Game Boy products contain a "integral 8 bit CISC CPU for compatibility," namely the same Sharp Z80-like CPU (not an official Zilog design) used in the Game Boy Color. It runs at 4 MHz when playing GB titles and 8 MHz when playing GBC titles. GBA does not contain a 6502 processor (as somebody changed); Z80 instructions are completely incompatible with MOS Technologies 6502 instructions. Z80 and 6502 are not members of the same family; their instruction sets and timings aren't even close. We're not sure whether the ARM7TDMI and the GBZ80 are on the same die.


Just for reference, the 6502 processor (with BCD mode removed) was used in NES; the Super NES used a [WDC 65C816]?. However, the existence of the PocketNES? emulator for GBA proves that NES emulation (and thus 6502 emulation) on ARM is far from impossible. --Damian Yerrick



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Last edited December 5, 2001 5:51 am by Damian Yerrick (diff)
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