On 1/7/2019 8:20 AM, allison via cctalk wrote:
snip...
made though more likely 74F, AS, or LS variant and of course CMOS 74ACT
(and cmos friends) as I just bought a bunch. Dip is getting harder to
get but
the various SMT packages are easy. Prices for 10 or more of a part are
cheap to cheaper from primary suppliers. The second tier suppliers are
often several times that.
I got ebay... The bottom of the heap.
I figure most of what I did back then is years before many here were born.
However I have enough NOS TTL 74LS, 74AS, 74F series to build several
machines.
I have been playing around with a early 70's TTL computer design
and 74LS181's are too slow by 30 ns. Using a BLACK BOX model for core
memory, I can get a 1.2us memory cycle using a 4.912 MHz raw clock
but I need a few 74Hxx's in there. Proms are 256x4 60 ns and 32x8 50 ns.
Do you have your 74Hxx spares? Eastern Europe still has a few on ebay
with reasonable shipping for 100% American Russian parts.
I'm still building, current project is a very compact Z80 CP/M system
using CF
for disk. Mine uses all Zilog CMOS for very low power. Its a variant of
the
Grant Searle Z80 with memory management added to utilize all of the
124k ram and eeprom. If you want go look there.
What do you use all that memory for?
Allison
The Chinese elves have been busy, My 5V 15 amp $20 power supply arrived
in the mail today. I have power to spare for my BUS and blinking lights.
Ben.
