Rockbox mail archiveSubject: Re: Another port, is it possible?
Re: Another port, is it possible?
From: Bluechip <csbluechip_at_gmail.com>
Date: Sat, 18 Aug 2007 11:05:33 +0100
At 10:47 18/08/2007, you wrote:
>Vladimir Pantelic wrote:
> > The data sheet says 8bit! There is a DSP that does the MP3 decoding and
> > a DMA controller, so most likely the z80 does little besides reading the
> > FAT filesystem and setting up the DMA to pipe data from Flash to the DSP.
>Actually the Z80 is an 8-bit CPU with some 16-bit extensions. For
>example it can combine six 8-bit registers into three 16-bit registers,
>and do some simple arithmetic on them (add/sub). This may not sound
>impressive, but it is way easier to program than a pure 8-bit CPU like
>the 6502/6510 which doesn't know of 16-bit at all.
There are registers other than BC DE and HL which behave as 16bit
"register-pairs", not least of all the index registers IX and IY,
there are also shadow registers and 16bit memory accessing
instructions to consider above and beyond a 'pure' 8bit machine.
Received on 2007-08-18