"Fred Cisin (XenoSoft)" wrote:
> On Thu, 10 May 2001, Megan wrote:
> > I have an old serial paper tape reader which runs with
> > 20ma and would like to use it to archive all my pdp-11
> > (and some pdp-8) paper tapes. But I need a converter...
> > Can anyone help? Any pointers to a simple schematic?
>
> As a quick and dirty alternative:
> The original IBM asynch adapter for the PC and XT was jumperable to
> operate as EIA OR 20 ma! You could use a PC with one jumpered 20ma plus
> one "regular" serial card as your converter.
>
This is also the quickest way to connect a TTY (20ma) to modem (RS-232);
by using a computer (PC) in the middle. Both schemes require a little
software. In the case of a tape reader, you must poll the 20 ma port and
when
data is on it transfer it to the serial port (one way). In the case of the
latter
(TTY/modem), you have to poll both ports and when data is present, send it
to the other port.
Both schemes are byte oriented but work as line buffers due to the nature of
the way devices operate.
Eric
>
> --
> Fred Cisin cisin_at_xenosoft.com
> XenoSoft http://www.xenosoft.com
> PO Box 1236 (510) 558-9366
> Berkeley, CA 94701-1236
Received on Fri May 11 2001 - 09:17:17 BST