On Thu, Jun 19, 2014 at 2:18 AM, Marco Rauhut <marco at familie-rauhut.eu> wrote: 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.