18 Feb
2009
18 Feb
'09
4:53 a.m.
Date: Tue, 17 Feb 2009 10:20:45 +0100
From: harten at injectstar.de
To: cctech at classiccmp.org
CC:
Subject: ASR33 as storage medium on PDP 11/05
Hi to all!
My PDP 11/05 came, when it was first sold, with an ASR 33
as the only console and storage medium.
Later it was modified to a system with RX02 Floppy and
one VT Terminal (connected to the 20mA loop but with 2400
baud instead of 110 as for the ASR).
Now i would like to reconnect the ASR (or another papertape
reader/puncher) to the system without having to screw up
the CPU to reduce the speed of the serial line interface.
I don't want the console-output to be printed on the ASR
but reading/punching papertapes would be fine.
As i remember DEC was selling its high speed reader
( PC11 ?) but only for fanfold tapes.
Maybe this can archived by adding one extra interface to
the unibus and a piece of software.
I'm not sure. The machine runs RT-11 V4.0
Regards
Axel Harten.
Maybe I am overlooking something, but is a simple DL11
interface not all that you need to connect a reader and puncher?
The PC11 interface (M7810) connects to the PC05, but if you have
a "standard" reader / puncher they can have an serial interface
(RS-whatever or current loop). And in that case, you can connect
to the the 11/05 using a simple UNIBUS async serial interface
module like the M7856.
You might want to disable the line time clock on the added SLU.
If the reader/pucher has a (8-bit) parallel interface it also has
a few handshake signals. It is fairly straight-forward to make a
parallel <-> serial interface. With a bit more effort you can
control the handshake lines to control the stepping speed of the
papertape movement. Less effort will cause the tape to move at
the reader/puncher speed, which might not match to a standard
baudrate.
With an SLU, no special software (drivers) are needed, unless
you want more control than simple start at begin of tape and
stop when tape is (completely) read (or all data punched).
Hope this helps (and is correct)
- Henk, PA8PDP