Al Kossow wrote: Yup, they are not quite suitable. The bus ports have a maximum tolerable voltage spec of 2.5V (not 5.5V) which of course will not work on the UNIBUS (termination is ~3.4V). I would recommend the Am26S10CN (also still in production in Pb free DIP) which is a true 5V bus transceiver. The only issue that has been identified is that the 26S10 has a somewhat higher bus receiver input threshold (2.0V+/-.25V) than does a legacy 8641 device (1.5V+/-0.2V). There was a discussion of this on cctech about 6mos back (search UNIBUS 26S10) for hits. Don North