1964 Antique MODEM Live Demo

[Jochen Kunz]

On Thu, 4 Jun 2009 15:15:24 -0400
Ethan Dicks <ethan.dicks at gmail.com> wrote:

> We had something like that happen with our Qbus COMBOARDs when an
> early customer installed theirs into a Qbus backplane that didn't
> provide -15V (which is, ISTR, most of them).  Things didn't make sense
> until we figured out the lack of negative voltage to the 1488s/1489s.
> Every Qboard after that had a DC-DC converter on it (and I still have
> dozens of those, new on the slab of foam).
Even DEC did it. The, IIRC, DHV11 QBus 8 line RS232 has a DC-DC
converter on it. I saw several DHV11 where the poted torroidal
inductivity of this discrete DC-DC converter was ripped of the PCB. 
-- 


tschüß,
       Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/