FPGA VAX update
mouse at Rodents.Montreal.QC.CA
Wed Nov 2 12:12:41 CST 2005
>> I guess nobody even considers building a computer from scratch. :(
> Wasn't there an article a looong time ago about a fellow who built
> his own CPU from TTL parts in BYTE or Microcomputing?
I dunno about that, but I once did just that. I took a digital
hardware design course, and as a term project I breadboarded a little
4-bit computer. (I think the whole class did likewise, but it was long
enough ago that memory is fuzzy.) Only 16 words of memory, and 4-bit
words at that, with 4-bit opcodes - not a terribly powerful machine,
but an extremely instructive one to build. All TTL; the most
complicated building block was a 4-bit ALU chip, a 74181 I think.
We also used what were easily the nicest breadboards I've ever used.
Real sockets for the chips, with socket pins brought out to jacks that
were basically miniature banana plug sockets; the wire connectors were
matching miniature banana plugs, and in particular were stackable the
way banana plugs are. All the connectors were gold-plated. The bench
unit the thing plugged into provided power, clock (frequency settable
from maybe 1Hz-50KHz, with a pushbutton for manual single pulses), a
bank of maybe 16 switches and 16 LEDs...a really pretty setup that was
a positive joy to use. Never seen anything nearly so nice since.
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