Re: A new life for my LA180.

[E. Groenenberg]

On Sun, January 22, 2017 16:59, william degnan wrote:
> If you have time can you post the simh info, what steps you took to
> connect
> to the printer from os/8?
>
> Bill Degnan
> twitter: billdeg
> vintagecomputer.net

Hi.

I'm not familiar with OS/8, but what I do for RSX-11M is to attach a
Unix serial line to a DZ11 line and within RSX I have a printer queue
which uses that DZ11 line for output.

What I need to try as well is to use the simh lpt device and see if
that will also work. I guess 'att lpt /dev/tty05' could do the trick.

Ed

> On Jan 22, 2017 2:25 AM, "Paul Anderson"  wrote:
>
>> Congrats!!
>>
>> The LA180 is probably my favorite DEC printer.
>>
>> On Sat, Jan 21, 2017 at 1:00 PM, E. Groenenberg 
>> wrote:
>>
>> > Not so much newsworthy, but 2 weeks ago I stumbled by accident on the
>> > serial option for the LA180 (Decprinter I). My offer was accepted and
>> I
>> > got the card 2 days ago. I installed it this afternoon and after
>> > configuring
>> > it and checking the jumpers on the main board, it now works as a
>> serial
>> > printer.
>> >
>> > Tomorrow I'm going to connect it with simh and see if printing jobs
>> > will get processed as well.
>> >
>> > Ed
>> > --
>> > Ik email, dus ik besta.
>> > BTC : 1Lk6141nvDKPxtCa5erfFyovsoJN2LKqNJ
>> >
>> >
>> >
>> >
>>
>

Ed
--
Ik email, dus ik besta.
BTC : 1Lk6141nvDKPxtCa5erfFyovsoJN2LKqNJ

Re: Attempt at Compaq keybord swap with a PC keyboard (failed)

[Randy Dawson]

This is the original Compaq I IBM PC clone, 8088



From: cctalk  on behalf of Fred Cisin 

Sent: Sunday, January 22, 2017 9:42 PM
To: General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Attempt at Compaq keybord swap with a PC keyboard (failed)

On Mon, 23 Jan 2017, Randy Dawson wrote:
> I have luggable with the famous Keytronics foam kepad rot.

WHAT model Compaq?

8088? 80286?

Attempt at Compaq keybord swap with a PC keyboard (failed)

[Randy Dawson]

I have luggable with the famous Keytronics foam kepad rot.


I am searching for the foam (have not found it yet), and on a lark, I tried 
using a PC keyboard.

In the PC keyboard, I soldered in a 7805 to take the Compaq 12V to 5V for the 
PC keyboard.

Traced the clock and data lines, hooked it all up and it does not work.

The Keytronics (compaq) keyboard either has a different protocol or signals 
inverted, I have not got that far with the scope yet to see the difference.


Has anybody found a source for the Keytronics mylar foam pads?


Randy

Re: quick omnibus question

[Brent Hilpert]

The two presentations look to be consistent to me, right down to the keyways.

The bitsavers/hack42 view is oriented is as if you held a board vertically with 
the connectors edge pointing towards you and the components on your right, the 
two faces are then folded out towards you.
The connectors go up A to D.
This view would also be a view from the bottom of the backplane.

The  8e/Docs 2-page extract is 180 degrees rotated from this.
So the connectors now go down A to D.


On 2017-Jan-22, at 3:15 PM, W2HX wrote:

> Before deleting this, someone much smarter than me should double check to 
> make sure I am right that the file is incorrect. It is a shame because it is 
> very nicely done. It even shows the keyways in the card. But it seems to be 
> backward to me.
> 
> I tried to find contact information for that hack42.nl site to suggest they 
> redo the otherwise useful file, but was not successful.
> Thank you
> Eugene
> 
> 
> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Al Kossow
> Sent: Sunday, January 22, 2017 5:59 PM
> To: cctalk@classiccmp.org
> Subject: Re: quick omnibus question
> 
> 
> 
> On 1/22/17 2:05 PM, W2HX wrote:
> 
>> I hope this email can be found by the next guy searching for the omnibus 
>> details so they can avoid wasting time.
>> THIS FILE IS WRONG
>> http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibu
>> s_legenda.pdf
>> 
>> This file shows the Omnibus signal locations CORRECTLY (extracted from 
>> a larger document) 
>> http://w2hx.com/x/VintageComp/PDP-8e/Docs/Omnibus_Card_Edge_Designatio
>> ns.pdf
>> 
>> 
>> 
>> 
> 
> 
> i will delete the file
> here is the original source
> http://www.classiccmp.org/pipermail/cctalk/2015-June/007475.html
> 

Re: quick omnibus question

[Noel Chiappa]

> From: Eugene (W2HX)

> Before deleting this, someone ... should double check to make sure I am
> right that the file is incorrect. ... But it seems to be backward to me.

Well, it is, and it isn't. The board is drawn with the 'bottom' (in DEC
nomenclature, for when the board is inserted in a backplane where the slots
run vertically) at the top of the drawing, and vice versa.

But, other than that, it appears to be correct - based on the keyed slots.
(So, the first land, at the bottom of the drawing, which is the 'top' of a
DEC board, normally, is AA. And the last - top of the drawing, 'bottom' of
the card when it's in vertical slot - is DV. Etc, etc.)

Noel

RE: quick omnibus question

[W2HX]

Before deleting this, someone much smarter than me should double check to make 
sure I am right that the file is incorrect. It is a shame because it is very 
nicely done. It even shows the keyways in the card. But it seems to be backward 
to me.

I tried to find contact information for that hack42.nl site to suggest they 
redo the otherwise useful file, but was not successful.
Thank you
Eugene


-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Al Kossow
Sent: Sunday, January 22, 2017 5:59 PM
To: cctalk@classiccmp.org
Subject: Re: quick omnibus question



On 1/22/17 2:05 PM, W2HX wrote:

> I hope this email can be found by the next guy searching for the omnibus 
> details so they can avoid wasting time.
> THIS FILE IS WRONG
> http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibu
> s_legenda.pdf
> 
> This file shows the Omnibus signal locations CORRECTLY (extracted from 
> a larger document) 
> http://w2hx.com/x/VintageComp/PDP-8e/Docs/Omnibus_Card_Edge_Designatio
> ns.pdf
> 
> 
> 
> 


i will delete the file
here is the original source
http://www.classiccmp.org/pipermail/cctalk/2015-June/007475.html

Re: quick omnibus question

[Al Kossow]

On 1/22/17 2:05 PM, W2HX wrote:

> I hope this email can be found by the next guy searching for the omnibus 
> details so they can avoid wasting time.
> THIS FILE IS WRONG
> http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf
> 
> This file shows the Omnibus signal locations CORRECTLY (extracted from a 
> larger document)
> http://w2hx.com/x/VintageComp/PDP-8e/Docs/Omnibus_Card_Edge_Designations.pdf
> 
> 
> 
> 


i will delete the file
here is the original source
http://www.classiccmp.org/pipermail/cctalk/2015-June/007475.html

Re: quick omnibus question

[Don North]

I would also do a cleaning of your empty backplane with a good vacuum cleaner 
nozzle. It is not uncommon for bits of conductive detritus to fall into the 
backplane over time. Given that the pins are adjacent on the connector it might 
be a possible cause.


Vacuuming out any stuff that has accumulated over time will be beneficial in any 
event. I have had mysterious 'opens' occur on a card slot when an old sticky 
label that lost is stick fell into the slot, and got wedged between a card pin 
and the connector.


Don

On 1/22/2017 2:05 PM, W2HX wrote:

Thanks to several who have made suggestions. Noel, Tony, Jim, and Paul thank 
you. The system has been very thoroughly cleaned and the PS has been load 
tested. The front panel has had some bulbs replaced as well.

I took all my boards (except the front panel) to a friend's house with a 
working 8e and tested each board in succession. I found that most boards worked 
but M8310 was not. And 8K of 32K was working fine. Above 8K there was a stuck 
bit in the core. But with 8K working we were able to boot OS8 with all of my 
boards except M8310 (oh, and I borrowed his serial tty card).

I did know about these MA7-MD4 bits that seem stuck together in my machine. But 
we did not see this problem in my friend's machine. So I am concluding the 
problem could be in one of 3 possible places. The 8310 card, the front panel, 
the bus itself.  Because these are the three components that were not part of 
the test in my friend's machine.

Next step was to see if these two bus lines are shorted somehow. After wasting 
time looking at a document that was wrong, I checked the M8310 card for shorts 
between MA7 and MD4 and none existed.

I am waiting on a douglas electronics card extender in the mail to check the 
bus itself. This issue could still be in the front panel or in some logic 
further upstream. This will be interesting to troubleshoot.

FYI
That omnibus_legenda.pdf file on bitsavers is CLEARLY erroneous based on what 
you guys are telling me and I found another document that indeed indicates that 
file is wrong. Too bad that this file is stored on bitsavers when it is 
incorrect.

I hope this email can be found by the next guy searching for the omnibus 
details so they can avoid wasting time.
THIS FILE IS WRONG
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

This file shows the Omnibus signal locations CORRECTLY (extracted from a larger 
document)
http://w2hx.com/x/VintageComp/PDP-8e/Docs/Omnibus_Card_Edge_Designations.pdf




-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of W2HX
Sent: Sunday, January 22, 2017 11:28 AM
To: General Discussion: On-Topic and Off-Topic Posts (cctalk@classiccmp.org)
Subject: quick omnibus question

Hi friends.
I am 100% new to my pdp8e and I am troubleshooting a problem.
The problem is that whenever address bit 7 I asserted, I also see MD bit 4 
asserted.

I am hoping there is a simple short somehow between these lines somewhere. I 
should mention that my setup has known working boards with the exception of 
M8310 does not work (all of my boards were tested in another machine one by 
one). So I am hoping the problem noted above might be occurring on the M8310 
board itself.

I found a document that describes the signals on the bus located here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be 
related?
So I decided to pull my 8310 and check the resistance between these signals on 
the edge of the board. However, I cannot seem to square the signals named in 
the PDF and what I see on the card edge connector on the board.

I am wondering if I am not understanding the PDF correctly. I have the board 
sitting on my table with the components facing up and the omnibus card edge is 
at the bottom of the card.  Going from left to right, do I have connectors ABCD 
or is it something else? Maybe DCBA?

Other than the reference PDF, is there another PDF that has a more detailed 
description of the bus and the signals?

Thanks
Eugene

Re: DS12887 pcb substitute with battery

[Chuck Guzis]

On 01/22/2017 01:49 PM, Maciej W. Rozycki wrote:

> A problem with reworking is there is sometimes very little clearance
>  available, so any modification has to be made in a clever way or you
> risk a short-circuit.  For example in DECstation 5000 systems their
> DS1287 chip is located in the TURBOchannel option slot area with the
> top of the chip almost reaching the solder side of the PCB of any
> option plugged in there.

Although there are several illustrations of the DS1287 rework where a
coin-cell holder was placed atop the chip, there's absolutely no reason
why that has to be so.  A couple of wire leads away to an off-board
battery holder, holding, say, an ER14250 half-AA.will work just fine and
keep the battery away from the PCB--or a couple of alkaline AA cells,
which should last a few years.  No reason to stick to lithium.

You know--"use your wetware".

--Chuck

RE: quick omnibus question

[W2HX]

Thanks to several who have made suggestions. Noel, Tony, Jim, and Paul thank 
you. The system has been very thoroughly cleaned and the PS has been load 
tested. The front panel has had some bulbs replaced as well.

I took all my boards (except the front panel) to a friend's house with a 
working 8e and tested each board in succession. I found that most boards worked 
but M8310 was not. And 8K of 32K was working fine. Above 8K there was a stuck 
bit in the core. But with 8K working we were able to boot OS8 with all of my 
boards except M8310 (oh, and I borrowed his serial tty card).

I did know about these MA7-MD4 bits that seem stuck together in my machine. But 
we did not see this problem in my friend's machine. So I am concluding the 
problem could be in one of 3 possible places. The 8310 card, the front panel, 
the bus itself.  Because these are the three components that were not part of 
the test in my friend's machine.

Next step was to see if these two bus lines are shorted somehow. After wasting 
time looking at a document that was wrong, I checked the M8310 card for shorts 
between MA7 and MD4 and none existed. 

I am waiting on a douglas electronics card extender in the mail to check the 
bus itself. This issue could still be in the front panel or in some logic 
further upstream. This will be interesting to troubleshoot.

FYI
That omnibus_legenda.pdf file on bitsavers is CLEARLY erroneous based on what 
you guys are telling me and I found another document that indeed indicates that 
file is wrong. Too bad that this file is stored on bitsavers when it is 
incorrect. 

I hope this email can be found by the next guy searching for the omnibus 
details so they can avoid wasting time.
THIS FILE IS WRONG
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

This file shows the Omnibus signal locations CORRECTLY (extracted from a larger 
document)
http://w2hx.com/x/VintageComp/PDP-8e/Docs/Omnibus_Card_Edge_Designations.pdf




-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of W2HX
Sent: Sunday, January 22, 2017 11:28 AM
To: General Discussion: On-Topic and Off-Topic Posts (cctalk@classiccmp.org)
Subject: quick omnibus question

Hi friends.
I am 100% new to my pdp8e and I am troubleshooting a problem.
The problem is that whenever address bit 7 I asserted, I also see MD bit 4 
asserted.

I am hoping there is a simple short somehow between these lines somewhere. I 
should mention that my setup has known working boards with the exception of 
M8310 does not work (all of my boards were tested in another machine one by 
one). So I am hoping the problem noted above might be occurring on the M8310 
board itself.

I found a document that describes the signals on the bus located here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be 
related?
So I decided to pull my 8310 and check the resistance between these signals on 
the edge of the board. However, I cannot seem to square the signals named in 
the PDF and what I see on the card edge connector on the board.

I am wondering if I am not understanding the PDF correctly. I have the board 
sitting on my table with the components facing up and the omnibus card edge is 
at the bottom of the card.  Going from left to right, do I have connectors ABCD 
or is it something else? Maybe DCBA?

Other than the reference PDF, is there another PDF that has a more detailed 
description of the bus and the signals?

Thanks
Eugene

RE: Altair

[Brad H]

Yes.  That remains an item on my hit list.

-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Sellam Ismail
Sent: Saturday, January 21, 2017 9:21 AM
To: cctalk@classiccmp.org
Subject: Altair

Hi Brad.

I saw your message on the ClassicCmp mailing list about desiring an Altair.
Are you still interested in one?

Sellam

Re: DS12887 pcb substitute with battery

[Maciej W. Rozycki]

On Sun, 22 Jan 2017, Chuck Guzis wrote:

> It's worth noting that the original post was about fabricating a
> replacement using the DS12885A RTC chip.  However, most old PCs used the
> DS1285 RTC (inside of a DS1287  module).  The DS12885A is supposed to be
> drop-in compatible with the DS1285, but apparently, in some cases is not.

 Of course it's not, because the DS12885 has additional 128 bytes of 
internal RAM addressable with the use of the AD6 line, which used to be a 
don't-care for the address register in the DS1285.  So if a system or a 
piece of software uses bit #6 of the address for some other purposes while 
letting it through down to the chip, expected to ignore it, then the 
effect will be different with the expanded chip compared to the original.  
Likewise with all the module variations made around these cores.

> So there's logic in reworking the old DS1287 modules, as the DS1285 chip
> is long out of production--you'll most likely have to be content with
> pulls or the occasional NOS lot.

 A problem with reworking is there is sometimes very little clearance 
available, so any modification has to be made in a clever way or you risk 
a short-circuit.  For example in DECstation 5000 systems their DS1287 chip 
is located in the TURBOchannel option slot area with the top of the chip 
almost reaching the solder side of the PCB of any option plugged in there.

  Maciej

Re: quick omnibus question

[Paul Anderson]

Hi Eugene,

You might want to test the over the top connectors. I don't remember the
part #, but they do go bad. They can be labeled and swapped with a spare if
have one. Just look to see if anything has changed after every change.

Dirty contacts and bad connections are always a problem.

I would remove the backplane. The foam under it is probably goo. I like to
lay the backplane upside on white paper, and lift one side up about an inch
and drop it.
This loosens up a lot of junk that air and other things don't get out.It's
amazing what you might find on the paper.

clean and inspect before replacing.

Good Luck!!

On Sun, Jan 22, 2017 at 10:27 AM, W2HX  wrote:

> Hi friends.
> I am 100% new to my pdp8e and I am troubleshooting a problem.
> The problem is that whenever address bit 7 I asserted, I also see MD bit 4
> asserted.
>
> I am hoping there is a simple short somehow between these lines somewhere.
> I should mention that my setup has known working boards with the exception
> of M8310 does not work (all of my boards were tested in another machine one
> by one). So I am hoping the problem noted above might be occurring on the
> M8310 board itself.
>
> I found a document that describes the signals on the bus located here:
> http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/
> pdp8e/Omnibus_legenda.pdf
>
> I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be
> related?
> So I decided to pull my 8310 and check the resistance between these
> signals on the edge of the board. However, I cannot seem to square the
> signals named in the PDF and what I see on the card edge connector on the
> board.
>
> I am wondering if I am not understanding the PDF correctly. I have the
> board sitting on my table with the components facing up and the omnibus
> card edge is at the bottom of the card.  Going from left to right, do I
> have connectors ABCD or is it something else? Maybe DCBA?
>
> Other than the reference PDF, is there another PDF that has a more
> detailed description of the bus and the signals?
>
> Thanks
> Eugene
>
>
>
>
>
>
>

Re: quick omnibus question

[jim stephens]

On 1/22/2017 12:17 PM, Tony Duell wrote:

On Sun, Jan 22, 2017 at 4:27 PM, W2HX  wrote:

Hi friends.
I am 100% new to my pdp8e and I am troubleshooting a problem.
The problem is that whenever address bit 7 I asserted, I also see MD bit 4 
asserted.

I am hoping there is a simple short somehow between these lines somewhere. I
should mention that my setup has known working boards with the exception of
M8310 does not work (all of my boards were tested in another machine one by 
one).
So I am hoping the problem noted above might be occurring on the M8310 board 
itself.

Could it be a short on the backplane? Or on the jumpers between the
backplanes if you
have 2 backplanes in the box (The standard 8/e box is designed to take
2 backplanes,
I believe the rear one was optional but almost always fitted).

My friend Sherman has a number of 8/E systems he is going to get going, 
and has a setup consisting of a frame, PS, and backplane.  He has a 
couple of single slot fixtures with switches at the moment which he used 
to ring out a potentially working front panel, and found a few failures 
there.


Of course after checking the backplane for shorts, and the PS.

He went to the M8330 (Timing board) and has fixed some things on that 
board.  he will cycle all board sets thru this system setup once he gets 
all the way to the processor.


As tony says, I'd start very basic with the backplane.  Especially if 
there is proximity of the signals there for your specific problem.


One system will be all scrap boards including a front panel which he 
retrieved just a tad too late from a scrap operation that had clipped 
the flip chip connectors.  A strap on Douglas board and rewiring will 
fix that one.


There are a lot of places in a system with most of the boards present 
that you can have failures, so hard to give a lot of suggestions.


I also hope the other main thing to test, the power supply was checked 
out and isn't playing games with you, though it doesn't seem likely it 
would make the short you suggest.


thanks
Jim


I found a document that describes the signals on the bus located here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be 
related?
So I decided to pull my 8310 and check the resistance between these signals on 
the
edge of the board. However, I cannot seem to square the signals named in the PDF
and what I see on the card edge connector on the board.

I am wondering if I am not understanding the PDF correctly. I have the board 
sitting
  on my table with the components facing up and the omnibus card edge is at the
  bottom of the card.  Going from left to right, do I have connectors ABCD or 
is it
something else? Maybe DCBA?

With the board like that, Connector A is on the right (so the order is
DCBA from left
to right, pin A is on the right of each connector, and side 1 is the
solder side.


Other than the reference PDF, is there another PDF that has a more detailed
description of the bus and the signals?

Do you have the Engineering Drawing/Printset (same thing, just 2
different names)
from bitsavers? There is also an excellent 3-volume PDP8/e (and /f,
/m) maintenance
manual on bitsavers (I have it on paper too). Volume 1 covers the CPU (which is
what you need now), Volume 2 is 'internal options', Volume 3 is
'external options. In
time you will need all of them.

-tony

DS12887 pcb substitute with battery

[Richard Sheppard]

I was hoping someone would make a M48Txx version for the old Suns etc.

Richard Sheppard

Re: quick omnibus question

[Tony Duell]

On Sun, Jan 22, 2017 at 4:27 PM, W2HX  wrote:
> Hi friends.
> I am 100% new to my pdp8e and I am troubleshooting a problem.
> The problem is that whenever address bit 7 I asserted, I also see MD bit 4 
> asserted.
>
> I am hoping there is a simple short somehow between these lines somewhere. I
> should mention that my setup has known working boards with the exception of
> M8310 does not work (all of my boards were tested in another machine one by 
> one).
> So I am hoping the problem noted above might be occurring on the M8310 board 
> itself.

Could it be a short on the backplane? Or on the jumpers between the
backplanes if you
have 2 backplanes in the box (The standard 8/e box is designed to take
2 backplanes,
I believe the rear one was optional but almost always fitted).


>
> I found a document that describes the signals on the bus located here:
> http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf
>
> I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be 
> related?
> So I decided to pull my 8310 and check the resistance between these signals 
> on the
> edge of the board. However, I cannot seem to square the signals named in the 
> PDF
> and what I see on the card edge connector on the board.
>
> I am wondering if I am not understanding the PDF correctly. I have the board 
> sitting
>  on my table with the components facing up and the omnibus card edge is at the
>  bottom of the card.  Going from left to right, do I have connectors ABCD or 
> is it
> something else? Maybe DCBA?

With the board like that, Connector A is on the right (so the order is
DCBA from left
to right, pin A is on the right of each connector, and side 1 is the
solder side.

>
> Other than the reference PDF, is there another PDF that has a more detailed
> description of the bus and the signals?

Do you have the Engineering Drawing/Printset (same thing, just 2
different names)
from bitsavers? There is also an excellent 3-volume PDP8/e (and /f,
/m) maintenance
manual on bitsavers (I have it on paper too). Volume 1 covers the CPU (which is
what you need now), Volume 2 is 'internal options', Volume 3 is
'external options. In
time you will need all of them.

-tony

Re: DS12887 pcb substitute with battery

[Tony Duell]

On Sun, Jan 22, 2017 at 5:16 PM, Jon Elson  wrote:
> On 01/22/2017 10:07 AM, Ali wrote:
>>
>> Al,
>> I thought the problem with switching these chips was that part of the ROM
>> code was embedded in them? I.e. it isn't just an issue of battery? Am I
>> wrong? If I am then why not use one of the replacement chips that are
>> available?
>>
> These don't have a lot of memory on them.  many early PCs stored some config
> info there, but generally the BIOS can reconstruct it if it isn't there.  I
> suppose there is a possibility that random data in the CMOS memory could
> cause the BIOS to try to use unavailable features and hang.  I don't think
> anybody put actual executable code in there.

On most PCs the RTC chip is mapped as I/O ports, not memory, so you couldn't
execute code from its RAM anyway. I suppose on (say) a 68000 based machine
you could (there is no separate I/O port address space on that processor) but
I have never seen it done.

-tony

Re: Transformer part ID please

[Tony Duell]

> Result! Whilst photographing the board to trace out that circuit (it's
> quicker for me than drawing it) I removed all the big capacitors. While they
> were out of circuit I tested them and discovered that not only was one dead
> in the -12V rail but also the through hole plating for another on the +12V
> rail had failed to a trace on the back of the board so neither the unknown
> 8-pin DIP or the LF351N were getting +12V.

Excellent!

>
> Fixed that and replaced the failed cap and now have -24V where it should be.
>
> If it helps with identification the unknown chip appears to be:
>
> 1 - GND
> 2 - 56k resistor to pin 3
> 3 - Gate of IRF523
> 4 - +12V via 10k resistor
> 5 - GND via decoupling cap
> 6 - connected to 2
> 7 - NC
> 8 - +12V
>
> That looks like an opamp to me, with bias pins connected to GND?

Does it? It looks like a 555 timer to me at first glance. I would have
expected another
capacitor from pins 2/6 to ground though.

1 Ground
2 Trigger (linked to threshold, and to output via a timing resistor)
3 Output (driving the MOSFET)
4 Reset/ (pulled high via a resistor)
5 Control Voltage (decoupled to ground)
6 Threshold (see 2)
7 Discharge (not used here)
8 Vcc


-tony

MSCP Qbus port layer doc sought

[Mouse]

I'm starting to pick up my KA630 emulator again.  In particular, I want
to give it MSCP disk.

I have various MSCP documentation files, but they talk about MSCP
proper.  None of them describe the Q-bus - nor even Unibus - port
drivers in enough detail for me to write an emulator; most of them
barely mention either Q-bus or Unibus.

I find I wrote a bunch of code, and I'm fairly sure it was based on a
doc file, but I cannot now find that doc file.  And I find the code
disagrees with NetBSD's MSCP support.  I tried to use the NetBSD driver
as documentation but end up with the response ring doing unexpected
things.

So, I'm looking for the Qbus port specification.  One of the text files
I found on bitsavers (a DEC-internal TMSCP document) says "See
UNIBUS/QBUS Storage Systems Port Specification for additional detail".
I also found a message to a simh mailing list, quoting an RQDX3
document which, in its "Applicable Documents" list, has

   o  UQSSP (Unibus/Qbus Storage Systems Port Specification)

Those sound like what I want.

Anyone happen to know where I might be able to find such a thing?

/~\ The ASCII Mouse
\ / Ribbon Campaign
 X  Against HTMLmo...@rodents-montreal.org
/ \ Email!   7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B

Re: DS12887 pcb substitute with battery

[Chuck Guzis]

On 01/22/2017 10:57 AM, allison wrote:
> I don't know about most people but this solution has been around for 
> decades.
> 
> I locate the battery on the failed part with a small magnet, then
> grind the epoxy down to it then pick it out with a sharp pointed
> tool.  Once I expose the connection point I older two wires then
> epoxy a small coin-cell holder in that spot and it s done.  I've done
> this more times than I care to count and its effective and the
> replacement battery some over 10 years old now have not failed.  But
> just in case I have a bag of NOS replacements (and pulls from
> socketed boards) all with dead batteries from age.  There is no magic
> to this.

It's worth noting that the original post was about fabricating a
replacement using the DS12885A RTC chip.  However, most old PCs used the
DS1285 RTC (inside of a DS1287  module).  The DS12885A is supposed to be
drop-in compatible with the DS1285, but apparently, in some cases is not.

So there's logic in reworking the old DS1287 modules, as the DS1285 chip
is long out of production--you'll most likely have to be content with
pulls or the occasional NOS lot.

--Chuck

Re: DS12887 pcb substitute with battery

[allison]

I don't know about most people but this solution has been around for
decades.

I locate the battery on the failed part with a small magnet, then grind the
epoxy down to it then pick it out with a sharp pointed tool.  Once I expose
the connection point I older two wires then epoxy a small coin-cell holder
in that spot and it s done.  I've done this more times than I care to count
and its effective and the replacement battery some over 10 years old
now have not failed.  But just in case I have a bag of NOS replacements
(and pulls from socketed boards) all with dead batteries from age.  There
is no magic to this.


Allison


On 01/22/2017 01:20 PM, Ali wrote:
> Jon,
> Then why not use a dip compatible version of the DS chip? I mean yes this 
> allows for switchable battery which is very nice but SMT soldering is not for 
> everyone.
>
> I wonder if there is a way to determine if there will be BIOS issues by 
> switching the DS12887?
>
>  Original message 
> From: Jon Elson  
> Date: 1/22/17  9:16 AM  (GMT-08:00) 
> To: gene...@classiccmp.org, "discuss...@classiccmp.org:On-Topic and Off-Topic 
> Posts"  
> Subject: Re: DS12887 pcb substitute with battery 
>
> On 01/22/2017 10:07 AM, Ali wrote:
>> Al,
>> I thought the problem with switching these chips was that part of the ROM 
>> code was embedded in them? I.e. it isn't just an issue of battery? Am I 
>> wrong? If I am then why not use one of the replacement chips that are 
>> available?
>>
> These don't have a lot of memory on them.  many early PCs 
> stored some config info there, but generally the BIOS can 
> reconstruct it if it isn't there.  I suppose there is a 
> possibility that random data in the CMOS memory could cause 
> the BIOS to try to use unavailable features and hang.  I 
> don't think anybody put actual executable code in there.
>
> Jon

Re: DS12887 pcb substitute with battery

[Ali]

Jon,
Then why not use a dip compatible version of the DS chip? I mean yes this 
allows for switchable battery which is very nice but SMT soldering is not for 
everyone.

I wonder if there is a way to determine if there will be BIOS issues by 
switching the DS12887?

 Original message 
From: Jon Elson  
Date: 1/22/17  9:16 AM  (GMT-08:00) 
To: gene...@classiccmp.org, "discuss...@classiccmp.org:On-Topic and Off-Topic 
Posts"  
Subject: Re: DS12887 pcb substitute with battery 

On 01/22/2017 10:07 AM, Ali wrote:
> Al,
> I thought the problem with switching these chips was that part of the ROM 
> code was embedded in them? I.e. it isn't just an issue of battery? Am I 
> wrong? If I am then why not use one of the replacement chips that are 
> available?
>
These don't have a lot of memory on them.  many early PCs 
stored some config info there, but generally the BIOS can 
reconstruct it if it isn't there.  I suppose there is a 
possibility that random data in the CMOS memory could cause 
the BIOS to try to use unavailable features and hang.  I 
don't think anybody put actual executable code in there.

Jon

Re: quick omnibus question

[Noel Chiappa]

> From: Eugene (W2HX)

> I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this
> be related?

"Rule #1: There are no concidences." :-)

> I have the board sitting on my table with the components facing up and
> the omnibus card edge is at the bottom of the card. Going from left to
> right, do I have connectors ABCD or is it something else? Maybe DCBA?

I don't know Omnibus, but I expect it follows the DEC connector conventions:

 http://gunkies.org/wiki/DEC_card_form_factor

and in that configuration, Pfrom left to right, the groups should be D to A.

Generally one goes from right to left, so A to D in that direction; the pins
go from A to V in that direction.

Noel

Re: Transformer part ID please

[Adrian Graham]

On 22/01/2017 07:31, "Tony Duell"  wrote:

>> The -24V regulator can be seen just above the 4 blue caps, The regulator
>> that can be seen under the black wire is a 7812. The LF351N has -12V present
>> at its bias outputs, the opamp to its right has no markings helpfully.
> 
> What about that IRF523? That is a power MOSFET transistor and might well
> be the chopper in the switching regulator circuit.

Result! Whilst photographing the board to trace out that circuit (it's
quicker for me than drawing it) I removed all the big capacitors. While they
were out of circuit I tested them and discovered that not only was one dead
in the -12V rail but also the through hole plating for another on the +12V
rail had failed to a trace on the back of the board so neither the unknown
8-pin DIP or the LF351N were getting +12V.

Fixed that and replaced the failed cap and now have -24V where it should be.

If it helps with identification the unknown chip appears to be:

1 - GND
2 - 56k resistor to pin 3
3 - Gate of IRF523
4 - +12V via 10k resistor
5 - GND via decoupling cap
6 - connected to 2
7 - NC
8 - +12V

That looks like an opamp to me, with bias pins connected to GND?

One more failed component off the list anyway.

-- 
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?

Re: DS12887 pcb substitute with battery

[Jon Elson]

On 01/22/2017 10:07 AM, Ali wrote:

Al,
I thought the problem with switching these chips was that part of the ROM code 
was embedded in them? I.e. it isn't just an issue of battery? Am I wrong? If I 
am then why not use one of the replacement chips that are available?

These don't have a lot of memory on them.  many early PCs 
stored some config info there, but generally the BIOS can 
reconstruct it if it isn't there.  I suppose there is a 
possibility that random data in the CMOS memory could cause 
the BIOS to try to use unavailable features and hang.  I 
don't think anybody put actual executable code in there.


Jon

quick omnibus question

[W2HX]

Hi friends.
I am 100% new to my pdp8e and I am troubleshooting a problem.
The problem is that whenever address bit 7 I asserted, I also see MD bit 4 
asserted.

I am hoping there is a simple short somehow between these lines somewhere. I 
should mention that my setup has known working boards with the exception of 
M8310 does not work (all of my boards were tested in another machine one by 
one). So I am hoping the problem noted above might be occurring on the M8310 
board itself.

I found a document that describes the signals on the bus located here:
http://bitsavers.informatik.uni-stuttgart.de/pdf/dec/pdp8/pdp8e/Omnibus_legenda.pdf

I noticed that B1J (MA7) is directly adjacent to B1K (MD4). Could this be 
related?
So I decided to pull my 8310 and check the resistance between these signals on 
the edge of the board. However, I cannot seem to square the signals named in 
the PDF and what I see on the card edge connector on the board.

I am wondering if I am not understanding the PDF correctly. I have the board 
sitting on my table with the components facing up and the omnibus card edge is 
at the bottom of the card.  Going from left to right, do I have connectors ABCD 
or is it something else? Maybe DCBA?

Other than the reference PDF, is there another PDF that has a more detailed 
description of the bus and the signals?

Thanks
Eugene

RE: DS12887 pcb substitute with battery

[Ali]

Al,
I thought the problem with switching these chips was that part of the ROM code 
was embedded in them? I.e. it isn't just an issue of battery? Am I wrong? If I 
am then why not use one of the replacement chips that are available? 
Thanks.
-Ali

 Original message 
From: Al Kossow  
Date: 1/21/17  12:12 PM  (GMT-08:00) 
To: "General Discussion: On-Topic and Off-Topic Posts"  
Subject: DS12887 pcb substitute with battery 

someone just pointed this out on vcfed

https://oshpark.com/shared_projects/qyNfzAMf

Re: A new life for my LA180.

[william degnan]

If you have time can you post the simh info, what steps you took to connect
to the printer from os/8?

Bill Degnan
twitter: billdeg
vintagecomputer.net
On Jan 22, 2017 2:25 AM, "Paul Anderson"  wrote:

> Congrats!!
>
> The LA180 is probably my favorite DEC printer.
>
> On Sat, Jan 21, 2017 at 1:00 PM, E. Groenenberg 
> wrote:
>
> > Not so much newsworthy, but 2 weeks ago I stumbled by accident on the
> > serial option for the LA180 (Decprinter I). My offer was accepted and I
> > got the card 2 days ago. I installed it this afternoon and after
> > configuring
> > it and checking the jumpers on the main board, it now works as a serial
> > printer.
> >
> > Tomorrow I'm going to connect it with simh and see if printing jobs
> > will get processed as well.
> >
> > Ed
> > --
> > Ik email, dus ik besta.
> > BTC : 1Lk6141nvDKPxtCa5erfFyovsoJN2LKqNJ
> >
> >
> >
> >
>

Re: Transformer part ID please

[Adrian Graham]

On 22/01/2017 07:31, "Tony Duell"  wrote:

>>> It looks to be part of a switching regulator circuit. Possibly to generate
>>> other voltages from the 5V line. Can you post a picture of more of the PCB
>>> around it.
>> 
>> Its second output goes via an IN4148 to the -24V regulator:
> 
> What do you mean by 'second output'? How many pins are used on this
> 'transformer'? If only 2 it is just a simple inductor, again possibly part of
> a swtiching regulator.

There's 5 pins (5th for keying I guess) with 2 separate windings and I've
just realised the 2nd winding (destination -24V) isn't fed from anywhere.
It's only a 2 sided board and there are no top traces under the part.

There's also some incomplete traces in that circuit so I wonder if there
were planned enhancements for a Mark II that never happened. I'm marking up
the back of the board for my own understanding as I type.

>> The -24V regulator can be seen just above the 4 blue caps, The regulator
>> that can be seen under the black wire is a 7812. The LF351N has -12V present
>> at its bias outputs, the opamp to its right has no markings helpfully.
> 
> What about that IRF523? That is a power MOSFET transistor and might well
> be the chopper in the switching regulator circuit.

It tests OK in my MOSFET tester.
 
> Why do you assume the other 8 pin IC is an op-amp?

Initially because of the way it's wired but I'm checking it now. Once I've
marked up where the traces go the picture should be clearer.

-- 
Adrian/Witchy
Binary Dinosaurs creator/curator
Www.binarydinosaurs.co.uk - the UK's biggest private home computer
collection?