Anton Aylward wrote:
Dave Howorth said the following on 10/24/2008 09:01 AM:
Errm, the PDP-11 was TTL integrated circuits <http://hampage.hu/pdp-11/1120.html> and LSI later.
Back then (1970's) TTL and ICs couldn't handle high current. TTY driver and disk interfaces were transistors, and even the boards that were TTL had a sprinkling of transistors. TTL simply couldn't handle those currents and voltages.
That would depend on whether a current loop or RS-232 interface was used. There were RS-232 transmitter & receiver ICs available back then, though some systems did use discrete transistors for RS-232. The Motorola MC1488 & MC1489 were popular RS-232 transmitter and receiver chips back then. -- Use OpenOffice.org <http://www.openoffice.org> -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org