23 Jun
1997
23 Jun
'97
2:26 p.m.
On Mon, 23 Jun 1997, William Donzelli wrote:
Well, I don't know - you could have used the 7485 and dip
switches/jumpers. 4 chips for 16-bit with one bit/word resolution
for I/O. You could have used 3 chips and ended up with a *standard*
16 register address space for an 6522 or such. I am sure they were
available in 1973. (But they wouldn't have been - ah - inexpensive.
BC
Ah - if you
think of 74LS68x and 14L4's as "current" with the introduction
of the Apple II, then that helps (to some extent) explain why you
don't like Wozniak's designs. Neither of these devices were even
gleams in anybody's eyes in 1977! The closest you'll come to programmable
logic in 1977 are bipolar PROM's. (Which Woz was no stranger to -
just take a look at the Disk ][ controller!)
Signetic (I think it was them) had some PAL like devices back in the
mid-1970s. I do not think they were as flexible as PALs, but they did
combine the best of the PROM and glue worlds for decoding schemes.