help needed: problem with UNIBUS access on my PDP-11/70

From: Tom Uban <uban_at_ubanproductions.com>
Date: Fri Jul 12 11:00:00 2002

At 08:27 AM 7/12/2002 +0200, you wrote:
<snip>

>Unfortunately, this installed PSU does not solve the problem.
>I still have the PAUSE led on with any access to 1777756x (read/write).

Have you tried to read from the bootstrap ROM locations? Since the
bootstrap is at the front of the bus, it might give you some insight if
it works properly and the DL11 at the rear of the bus does not.

>My new question.
>When you have an 11/70 without the floating point boards and you want
>to install the FP option, you do the following things.
>- carefully slide the 4 FP boards in the correct position,
> in the slots 2-3-4-5.
>- install an H744 in the upper power supply, position A
> (nearest to the transformer compartment) and connect it to P9.
>- is there something else you shuld do ?

Usually, there are some jumpers on the main CPU boards which will
have to change when an option such as FP is installed or removed.
For instance, if you look at your M8132 (IR DECODE & COND CODES
IRC) board, you will see that Jumper W1 should be installed if the FP
is installed (and removed otherwise). There may be other jumpers and
or switches which should be changed when installing/removing the FP,
you will have to do some research, but you should be able to tell if the
FP was originally installed (or not) based on the one jumper on M8132.

--tom

>TIA,
>- Henk.
Received on Fri Jul 12 2002 - 11:00:00 BST