I need PDP-11/34A Help Again (Suprise Suprise)

From: Andreas Freiherr <Andreas.Freiherr_at_Vishay.com>
Date: Thu Jan 24 14:59:02 2002

Owen,

still interested in getting your PDP-11/34 to work? - I am just about to
reassemble mine after relocation.

RUN light off and display 000002 means the processor halted at memory
location 2, so it has probably executed a HALT instruction (opcode
000000) from location 0.

Try this: enter 773000, load this address, and then press START. Since
773000 is the standard start address for a bootstrap ROM, this should
get you a response on the console terminal attached to the DL-11W.
(Don't remember which, but I think it should ask for a two-letter device
code to boot.)

BTW: The DL11-W has a 20mA interface as well as RS-232. (Note the "1488"
and "1489" chips being present as well as a number of transistors and
other discrete components.) Which on is used depends on the cable: the
plug will have some wire connections to code it for either 20mA current
loop or RS-232 / V.24. If you have an original cable with the usual
DB-25 connector, it should be OK: current loop used a completely
different 6-pin connector.

For the settings at the terminal, I don't know this particular type, but
with most DEC lines you should be best prepared if you use XON/XOFF
handshake ("Main Rcv Hndsk" / "Main Xmt Hdsk"). Since at PDP-11 times,
the 8th bit was commonly used as a parity bit, set your terminal to
ignore this. Otherwise, you may get garbage characters instead of about
every second readable character.

A RS-232 break signal (certain voltage level applied for a certain time,
not a sequence of bits!) can sometimes cause a PDP-11 to HALT (depending
on settings on the interface board), so you may want to avoid this...
(perhaps by choosing an appropriate setting for the "Disconnect" option
for now?)

So much from memory. If you need more details, let me know, and I'll dig
into the docs.

Good luck,
Andreas

--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com
Received on Thu Jan 24 2002 - 14:59:02 GMT

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