14 Mar
2013
14 Mar
'13
2 p.m.
The early PDP-11 uses a ?DEC 1801 UART? in multiple modules. I?ve had no
luck identifying a comparable chip that could be substituted when doing
repairs as there?s a remarkable dearth of information regarding the
characteristics of this part, excepting the pin-out as seen in engineering
drawings. (No, I haven?t yet tried pin-out matching ... next step.)
Ideally the part would be both HW and SW compatible, but clearly SW
compatibility is key!
Does anyone have any experience with this part, repairing boards where this
part has failed, or other words-of-wisdom to offer?
Thanks,
paul
15 Mar
15 Mar
3:51 a.m.
On Thu, Mar 14, 2013 at 2:00 PM, Paul Birkel <pbirkel at gmail.com> wrote:
The early PDP-11 uses a ?DEC 1801 UART? in multiple
modules. I?ve had no
luck identifying a comparable chip that could be substituted when doing
repairs as there?s a remarkable dearth of information regarding the
characteristics of this part, excepting the pin-out as seen in engineering
drawings. (No, I haven?t yet tried pin-out matching ... next step.)
I haven't checked schematics myself, but the TR1602 dates back to
1971. It's a 40-pin UART, the first, IIRC.
Datasheets aren't hard to find for it. The receive bus is pins 5-12, the
transmit bus is pins 26-33, and for power, +5 is on pin 1, -12 is on pin 2
and GND is on pin 3.
-ethan
4:10 a.m.
On Fri, Mar 15, 2013 at 03:51:00AM -0400, Ethan Dicks wrote:
On Thu, Mar 14, 2013 at 2:00 PM, Paul Birkel
<pbirkel at gmail.com> wrote:
I just looked at a couple of schematics and the pinout looks similar/identical
to the GI AY5-1013 too. Might be easier to find since they sure used to be
plentiful (Radio Shack sold them, and the AY3-1015 5V-only version too which
I think is pin-compatible).
Software compatibility is almost meaningless since everything is brought out to
individual pins (there's no register file like in an 8250), so bit order etc.
is up to the designer. IIRC the parity/etc. controls are on transparent
latches so you can make that be a writable register, or else enable it all the
time and use DIP switches etc. (which makes more sense for typical DEC
applications).
John Wilson
D Bit
The early PDP-11 uses a ?DEC 1801 UART? in
multiple modules.
I haven't checked schematics myself, but the TR1602 dates back to
1971. It's a 40-pin UART, the first, IIRC.
Datasheets aren't hard to find for it. The receive bus is pins 5-12, the
transmit bus is pins 26-33, and for power, +5 is on pin 1, -12 is on pin 2
and GND is on pin 3. 
7:22 a.m.
Paul Birkel wrote:
The early PDP-11 uses a ?DEC 1801 UART? in multiple
modules. I?ve had no
luck identifying a comparable chip that could be substituted when doing
repairs as there?s a remarkable dearth of information regarding the
characteristics of this part, excepting the pin-out as seen in engineering
drawings. (No, I haven?t yet tried pin-out matching ... next step.)
Ideally the part would be both HW and SW compatible, but clearly SW
compatibility is key!
Does anyone have any experience with this part, repairing boards where this
part has failed, or other words-of-wisdom to offer?
Thanks,
paul
The Eastern Block TESLA MHB1012 is also a compatible Part, have a few of
them. There is no SW Compatibility at all since the part is in no way
programmable, every detail is configured trough control signals.
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583
www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741
16 Mar
16 Mar
3:40 p.m.
Thank you Ethan, John, and Holm. It looks like I have a number of options
in the appropriate era; the variations seem to be only in terms of whether
the Vdd of -12v is required (process-based I presume) and the max.
supported speed (not exactly an issue with a 300 baud, more-or-less board
:-<). I'll socket it and try a suitable candidate then. Doesn't seem that
much can/should go wrong. We'll see about that ...
On Fri, Mar 15, 2013 at 7:22 AM, Holm Tiffe <holm at freibergnet.de> wrote:
Paul Birkel wrote:
The early PDP-11 uses a ?DEC 1801 UART? in
multiple modules. I?ve had no
luck identifying a comparable chip that could be substituted when doing
repairs as there?s a remarkable dearth of information regarding the
characteristics of this part, excepting the pin-out as seen in
engineering
drawings. (No, I haven?t yet tried pin-out
matching ... next step.)
Ideally the part would be both HW and SW compatible, but clearly SW
compatibility is key!
Does anyone have any experience with this part, repairing boards where
this
part has failed, or other words-of-wisdom to
offer?
Thanks,
paul
The Eastern Block TESLA MHB1012 is also a compatible Part, have a few of
them. There is no SW Compatibility at all since the part is in no way
programmable, every detail is configured trough control signals.
Regards,
Holm
--
Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe,
Freiberger Stra?e 42, 09600 Obersch?na, USt-Id: DE253710583
www.tsht.de, info at tsht.de, Fax +49 3731 74200, Mobil: 0172 8790 741
4147
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4 comments
4 participants
participants (4)
-
ethan.dicks＠gmail.com -
holm＠freibergnet.de -
pbirkel＠gmail.com -
wilson＠dbit.com