24 Sep
2014
24 Sep
'14
1:45 p.m.
On Sep 24, 2014, at 3:46 PM, Roe Peterson <roeapeterson at gmail.com> wrote:
Does anyone know offhand what the -15 volt power
supply was used for in a BA11-K pdp11/34 enclosure?
Thanks.
Some guesses: (a) core memory circuitry, (b) RS-232 drivers. (RS-232 requires + and - 15
volt, give or take. Modern transceiver chips produce those voltages on-chip, but anything
more than 10 or so years old relies on +/- 15V supplies to feed the RS232 driver
circuits.)
paul