Fw: [sdiy] Anybody using Atmel AVR?

[Phil Harbison]

Roy wrote:
> Yeah,  but when these days would you possibly want to
> impose any wait states on one of those chips? [...]

These days I would not use those parts in a new design,
but we were using them in 1979. We never had a problem
finding static RAM that could keep up with a 1 or 2MHz
6502. The problem was dynamic RAM. What do you do when
you need to refresh the RAM? It is fairly easy to piggy-
back a refresh cycle onto every memory cycle (and the
Z-80 would even do this for you) but not very practical
if that means doubling the duration of each memory cycle.

But I was thinking more about the CPU implementation.
If you are implementing those complex addressing modes
it would be nice to have more, shorter clock cycles per
instruction since it probably doesn't take a microsecond
to add a base address to an index register.

Roy J. Tellason wrote:
> So what fun sdiy things can we do with them? [...] but I
> have *lots* of 6502-family stuff,  including the cpu,
> 6510 cpu,  6522,  6526,  6551,  etc.

IIRC, the 6522 had a shift register which I always thought
could be used to build a primitive LAN or control bus. You
might build an array of voice cards (each with a 6502, 6522,
EEPROM and RAM) controlled by a master 6502 with MIDI I/O.

> and also the same with z80-family stuff...

ACK!!! Torment me not with the Z-parts!

-- 
Phil Harbison <--- wrote *way* too much Z-80 assembly code