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.
BC
