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Old 09-29-2009, 06:32 PM   #1
Aphex19
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Default Any GB emulator authors out there?

hey, just on the off chance of catching someone who alot knows about the GameBoy opcodes, I just want to ask a question.

Im currently writing a GB emu in C++ and have plenty of reliable infomation to go buy, apart from one thing which has bugged me.

Can someone just tell me the amount of opcodes the gameboy has because so far I have taken acocunt of about 300-400 and will be emulating in all (including the opcodes that are 2 bytes) about 500 or 600. Although, another emulator author says there are only around 300....

Im just confused. Surely something isnt right here.
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Old 09-29-2009, 08:22 PM   #2
Reaper man
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The GB has an 8bit CPU. How the hell could it have more than 256 opcodes?
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Old 09-29-2009, 08:34 PM   #3
Aphex19
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Some of the opcodes are 16 bit. Such as CB 01 - CB FF. They are all 16 bit ops.
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Old 10-01-2009, 03:17 AM   #4
Laternenschein
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Quote:
Originally Posted by Aphex19 View Post
Some of the opcodes are 16 bit. Such as CB 01 - CB FF. They are all 16 bit ops.
And that's the only one, see attachment. 0x10 0x00 is not a single opcode. It's because the CPU has a bug that prevents it from executing the opcode after 0x10, so official docs suggest that it be a nop 0x00.
Attached Files
File Type: txt opcodes.txt (8.2 KB, 289 views)
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Old 10-04-2009, 06:41 PM   #5
Aphex19
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In my emulator, I have opcode 10 down as a read memory instruction.

LD A, (BC)

I use some pretty reliable sources for this but i guess only time will tell, when i eventually get this damn gb emu working
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Old 10-09-2009, 01:14 PM   #6
Laternenschein
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We're talking hexadecimal here. Decimal is for lusers.
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Old 10-14-2009, 04:19 PM   #7
nensondubois
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Could you write an SPC driver for those games that use Super Game Boy enhanced music?
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