rodsmallwood at btconnect.com
Tue Apr 14 09:36:53 CDT 2009
Thanks for the reply.
The list backlog and subsequent mail tsunami means it's a while since I last
had a go at the system. I'll run it up tonight and verify what happens.
Here's what I can remember. In the manual there's a simple test which counts
up in the accumulator. It's entered through the switch register.
First you set the switch register to 0000 (Octal) and press the load
address. Next you set up the first instruction in the SR and then lift DEP
(deposit). The address is auto incremented by one and you enter the next
instruction. After the last instruction is in then you load the start
address and hit clear and continue and it should count up.
It was working but it stopped. If you do examine rather than start you find
the memory locations are (I think) still zero.
The memory is core with four sets of three boards (4K) making 16K total.
Swapping one set of boards with another makes no difference.
The switch reg. must be working because memory addresses can be set up.
I suspect the memory data bus or associated buffers may have something to do
I'll do a detailed check to-night
I collect and restore old computer equipment with this logo.
From: cctech-bounces at classiccmp.org [mailto:cctech-bounces at classiccmp.org]
On Behalf Of Philipp Hachtmann
Sent: 04 April 2009 12:29
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: pdp-8/e fault
> Since core
> memory reads are destructive, we can eliminate some core issues if you
> say that core can be read repeatedly without it's contents changing. It
> could be a problem with the path between the switch register and the
> memory data bus.
But he wrote that the data displays correctly. The 8/e display shows the
state of the memory data bus. My first idea would be to check for bad
contacts. And think about the memory control.
And? Can you read out memory? Does it change?
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