19 Jun
2014
19 Jun
'14
10:09 a.m.
On Thu, Jun 19, 2014 at 2:18 AM, Marco Rauhut
<marco at familie-rauhut.eu>
wrote:
I just recently repaired a DEC TU60 tape drive. It contained N8271
chips in the CRC logic. One of them was bad.
I replaced it with a 74179 which I bought on EBAY. As far as I
understand they are identical.
http://www.datormuseum.se/computers/digital-equipment-corporation/pdp-11-04
i have here a PDP8/E with a defective M8300
Mayjor Register board. The
problem is a DEC8271 shift register that is used for bit 0 - 3 in program
counter register.
Do anyone know a modern equivalent for the DEC8271?
It's a Signetics 8271. The full Signetics part number is N8271B for
plastic package or N8271E for ceramic, or "S" prefix rather than "N"
for
-55C to +125C temperature range.
There is no "modern equivalent". The 74LS395A has similar functionality
except that it has a single clock input and a load/shift control, whereas
the 8271 has separate load and shift clocks. And the pinout is completely
different.
If you can't get an 8271, you could program a PAL to do the same thing,
though it's possible that the much higher speed of the PAL could cause
problems.
I wouldn't advise trying to substitute the Intel 8271.