10 Mar
2005
10 Mar
'05
12:50 p.m.
I'm looking to drive both Unibus and Qbus with 5v tolerant
Spartan2 (2.5v) fpga I/Os... anyone done this before?
I'v heard of people using 4000 series cmos(??) in instead
of the approved DS8640/1, DC005, DEC9881, DEC380 etc
Spartan2 3.3V CMOS I/O is 5v tolerant without external resistors,
but since lines may have to be series source terminated anyways,
Spartan2e or Spartan3 might work as well.. Ideally I'm looking
to use the same part for both Unibus and Qbus, possibly fiddling Vref.