22 Aug
2006
22 Aug
'06
3:17 p.m.
There's one on eBay at the moment - Item 280020173050 - with a
picture clearly showing the rear with a DC out connector. It appears
to only be +/- 5V from the labeling, which I would have thought
insufficient to run a Beeb. So what WAS it used for??
That's all a Beeb needs. +5V for the logic and the +ve supply to the
RS423 buffers, -5V for some of the analogue stuff and the -ve supply to
the RS423 buffers. The normal PSU just gives out those 2 voltages.
A Beeb will actually boot with just the +5V line connected, but you'll
have no sound, and the serial port doesn't work. I found this out in the
obvious way when restoring my Acorn Cambridge Workstation (which has a
Beeb B+ in the bottom, of course)
-tony