17 Jan
2014
17 Jan
'14
6:38 a.m.
Hi all,
Recently, my PDP-8/E has been acting funny. I finally had some time tonight
to run a memory test and found that all addresses matching the pattern
XX5XX read back all zeros. Everything else tests fine. I swapped the XY
driver board (G233) and found that the problem went away.
I can't seem to locate a schematic online. My PDP-8/E preliminary
maintenance manual only describes the G227, for the 4k core board. Can
anyone help with a schematic, or judging from the symptom, point me to a
particular area on the board? I've got a 'scope and should be able to
diagnose it if I know where to start looking.
Thanks,
Kyle
17 Jan
17 Jan
7:43 a.m.
From: Kyle Owen: Thursday, January 16, 2014 10:38 PM
Recently, my PDP-8/E has been acting funny. I finally
had some time tonight
to run a memory test and found that all addresses matching the pattern
XX5XX read back all zeros. Everything else tests fine. I swapped the XY
driver board (G233) and found that the problem went away.
I can't seem to locate a schematic online. My PDP-8/E preliminary
maintenance manual only describes the G227, for the 4k core board. Can
anyone help with a schematic, or judging from the symptom, point me to a
particular area on the board? I've got a 'scope and should be able to
diagnose it if I know where to start looking.
Are you looking for this?
bitsavers.org/pdf/dec/pdp8/pdp8e/MM8-EJ_Engineering_Drawings_May73.pdf
Vince
4:11 p.m.
On Fri, Jan 17, 2014 at 1:43 AM, Vincent Slyngstad <vrs at msn.com> wrote:
Are you looking for this?
bitsavers.org/pdf/dec/pdp8/pdp8e/MM8-EJ_Engineering_Drawings_May73.pdf
Vince
Thanks Vince. I apparently struggle with the Internet when I'm tired. :)
Much appreciated,
Kyle
8 p.m.
From: Kyle Owen: Friday, January 17, 2014 8:11 AM
On Fri, Jan 17, 2014 at 1:43 AM, Vincent Slyngstad
<vrs at msn.com> wrote:
No problem. Somehow I had failed to pick up a copy of that particular document
myself. Which is odd, as I have a few of the board sets for my 8/E.
Vince
Are you looking for this?
bitsavers.org/pdf/dec/pdp8/pdp8e/MM8-EJ_Engineering_Drawings_May73.pdf
Thanks Vince. I apparently struggle with the Internet when I'm tired. :)
Much appreciated, 
6:52 p.m.
Hi, I have the drawing for the GG233, I only have an A4 scanner but can
scanthem if this will help but you will have to to do a "stick it together
job"
sounds like you have decoder problem so it may be one of the many 7442, s ,
will have to check to see which one though.
Dave
----- Original Message -----
From: "Kyle Owen" <kylevowen at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Friday, January 17, 2014 6:38 AM
Subject: PDP-8/E MM8EJ G233 Troubles
Hi all,
Recently, my PDP-8/E has been acting funny. I finally had some time
tonight
to run a memory test and found that all addresses matching the pattern
XX5XX read back all zeros. Everything else tests fine. I swapped the XY
driver board (G233) and found that the problem went away.
I can't seem to locate a schematic online. My PDP-8/E preliminary
maintenance manual only describes the G227, for the 4k core board. Can
anyone help with a schematic, or judging from the symptom, point me to a
particular area on the board? I've got a 'scope and should be able to
diagnose it if I know where to start looking.
Thanks,
Kyle
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.2247 / Virus Database: 3681/6511 - Release Date: 01/17/14
7:05 p.m.
E1 and E7 do the ma3,4 and 5 decode
Dave
----- Original Message -----
From: "Kyle Owen" <kylevowen at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Friday, January 17, 2014 6:38 AM
Subject: PDP-8/E MM8EJ G233 Troubles
Hi all,
Recently, my PDP-8/E has been acting funny. I finally had some time
tonight
to run a memory test and found that all addresses matching the pattern
XX5XX read back all zeros. Everything else tests fine. I swapped the XY
driver board (G233) and found that the problem went away.
I can't seem to locate a schematic online. My PDP-8/E preliminary
maintenance manual only describes the G227, for the 4k core board. Can
anyone help with a schematic, or judging from the symptom, point me to a
particular area on the board? I've got a 'scope and should be able to
diagnose it if I know where to start looking.
Thanks,
Kyle
-----
No virus found in this message.
Checked by AVG - www.avg.com
Version: 2012.0.2247 / Virus Database: 3681/6511 - Release Date: 01/17/14
18 Jan
18 Jan
8:29 a.m.
On Fri, Jan 17, 2014 at 1:05 PM, David Humphries <david at hheng.plus.com>wrote:
E1 and E7 do the ma3,4 and 5 decode
Dave
With a pattern like XX5XX, wouldn't I need to look at MA6 through MA8?
Looks like that'd be E50 and E43. I'll be checking those when I get back to
the computer in a couple of days.
Kyle
9:01 a.m.
On Jan 18, 2014 2:29 AM, "Kyle Owen" <kylevowen at gmail.com> wrote:
Looks
like that'd be E50 and E43. I'll be checking those when I get back to
the computer in a couple of days.
On Fri, Jan 17, 2014 at 1:05 PM, David Humphries <david at hheng.plus.com>
wrote:
E1 and E7 do the ma3,4 and 5 decode
Dave
With a pattern like XX5XX, wouldn't I need to look at MA6 through MA8?
Kyle
I'm mistaken; you are right, Dave. I tend to forget the important fact that
DEC labeled bits increasing from left to right. Argh!
Kyle
19 Jan
19 Jan
1:28 p.m.
I don't like those decoders :-)
On 17.01.2014 20:05, David Humphries wrote:
E1 and E7 do the ma3,4 and 5 decode
Dave
----- Original Message ----- From: "Kyle Owen" <kylevowen at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Sent: Friday, January 17, 2014 6:38 AM
Subject: PDP-8/E MM8EJ G233 Troubles
> Hi all,
>
> Recently, my PDP-8/E has been acting funny. I finally had some time tonight
> to run a memory test and found that all addresses matching the pattern
> XX5XX read back all zeros. Everything else tests fine. I swapped the XY
> driver board (G233) and found that the problem went away.
>
> I can't seem to locate a schematic online. My PDP-8/E preliminary
> maintenance manual only describes the G227, for the 4k core board. Can
> anyone help with a schematic, or judging from the symptom, point me to a
> particular area on the board? I've got a 'scope and should be able to
> diagnose it if I know where to start looking.
>
> Thanks,
>
> Kyle
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2012.0.2247 / Virus Database: 3681/6511 - Release Date: 01/17/14
>
--
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8 comments
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