Re: A86: gbdk

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Re: A86: gbdk


At 15:16 1999-10-06 -0400, you wrote:
>
>Clem (or anyone):
>
>The Gameboy doesn't have a Z80?  I could have sworn that the gameboy had a 
>z80 or z180... at least that's what I think I heard Nintendo and the makers 
>of NO$GMB say.  Hmmm.  I know that the new gameboy won't have a z80, but i 
>thought that the original had like 4mhz z80 and GBC had like 6.7 mhz z80...  
>Please clarify.  And if so then why have several TI-8X z80 developers (Clem, 
>Andreas Ess, Matt Shepcar) started to also program for gameboy?  Is it 
>similar or just another new exciting platform/language to learn?

Seems this issue has to be straightened out once every second month or so...

The CPU on the Game Boy resembles most of all the Intel 8080
when comparing the opcodes, but misses a few instructions (exchange
instructions; maybe others). It uses the Z80 mnemonic though.
For instance, on the 8080 the "ld" instruction was "mov",
the register were called by numbers instead of letters etc.

The Z80 contains all 8080 instructions (same opcodes) + lots of new ones.
Thus, there are LOTS of Z80 instructions missing on the GB CPU.
Also, it runs at 4.2MHz/8.4MHz.

--
Jimmy Mårdell                   "God made machine language;
mailto:yarin@acc.umu.se          all the rest is the work of man."
http://www.acc.umu.se/~yarin/
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