On 3/30/25 6:44 PM, Martin Bishop wrote:
Your driver design sketches and comments are substantially on the money. Thank you for
making them public. However, an effective implementation in discrete components would
not be "tiny" - even with 0402 passives and a pick / place machine on the case
ridgham via cctalk [mailto:cctalk@classiccmp.org]
Sent: 31 March 2025 13:02
To: General Discussion: On-Topic and Off-Topic Posts
Cc: David Bridgham
Subject: [cctalk] Re: DEC bus transceivers
On 3/30/25 6:44 PM, Martin Bishop wrote:
> Your driver design sketches and comments are substantiall
Indeed. I think I have sixteen dZ11 boards that I could part for a unibone
On March 30, 2025 11:49:44 PM CDT, Paul Anderson via cctalk
wrote:
>Does anyone have a list of what boards they were used on?
>
>I do have some boards I'm planning or recycling (I know, I shouldn't say
>that, especially h
Does anyone have a list of what boards they were used on?
I do have some boards I'm planning or recycling (I know, I shouldn't say
that, especially here, but most are common boards nobody uses anymore.) I
haven't looked at the IPBs yet, but did plan on pulling some of the chips.
On Sun, Mar 30,
nt: 30 March 2025 22:44
> To: General Discussion: On-Topic and Off-Topic Posts <
> cctalk@classiccmp.org>
> Cc: Martin Bishop
> Subject: [cctalk] Re: DEC bus transceivers (was: DEC Unibus variants)
>
> David
>
> You will have seen my response to shadooo / Andreas.
>
Sent: 30 March 2025 22:44
To: General Discussion: On-Topic and Off-Topic Posts
Cc: Martin Bishop
Subject: [cctalk] Re: DEC bus transceivers (was: DEC Unibus variants)
David
You will have seen my response to shadooo / Andreas.
Occasional NOS in small quantities excepted, I'm also
Should you make further progress very interested to hear of it
Best Regards
Martin
-Original Message-
From: David Bridgham via cctalk [mailto:cctalk@classiccmp.org]
Sent: 30 March 2025 14:59
To: Martin Bishop via cctalk
Cc: David Bridgham
Subject: [cctalk] DEC bus transceivers (was: DEC
On 3/29/25 7:29 PM, Martin Bishop via cctalk wrote:
The why not use a UniBone comment has merit, what will your (FPGA)
implementation add ?
I'm not shad but I've also been working on a somewhat similar
FPGA-based board called the USIC / QSIC. We started working on it
before the UniBone
I have thousands of NOS chips here that i hope to finish going through. I
have no idea how many bus transceivers are in there. These were intended
for projects I don't know if I'll ever get around to.
There are a lot of NOS out there at a variety of prices. The common 74xx
are mostly there and fai
> From: Philipp Hachtmann
> that one posting sounded a lot like that, sorry.
OK.
> Do you have a source where there are still 30k chips sitting and
> waiting?
It was ~30K a couple of months ago. I checked about a week ago, and it was
down to ~26K (IIRC).
Although, like I said,
On 10/26/2016 04:54 PM, Noel Chiappa wrote:
> From: Philipp Hachtmann
> Very enlightening.
> You're hoarding interface ICs with commercial second thoughts
If you think either Guy, or Dave and I, expect to make much money selling the
QBUS/UNIBUS boards we are working on, you are se
Hi all,
On my road trip earlier this year one of the docs I snagged was a ring
binder of Foxboro
Integrated Circuits dated 10/73, Revision A, one of 200 copies. It covers chip
characteristics
and compatibility cross references.
This was part of the doc set for the Foxboro FOX 2/10 (PDP-11/15)
On 10/26/2016 12:40 PM, Noel Chiappa wrote:
> Re: DEC bus transceivers
> > From: allison
>
> > Actually since about 1987 I've used about 1200 pieces of the 8641 alone
> > repairing boards at the commercial level.
>
> Well, that's over almost 30
On 10/26/16 10:54 AM, Noel Chiappa wrote:
> From: Philipp Hachtmann
> Very enlightening.
> You're hoarding interface ICs with commercial second thoughts
If you think either Guy, or Dave and I, expect to make much money selling the
QBUS/UNIBUS boards we are working on, you are ser
Re: DEC bus transceivers
> From: allison
> Actually since about 1987 I've used about 1200 pieces of the 8641 alone
> repairing boards at the commercial level.
Well, that's over almost 30 years - and your total from that period is about
4% of the remaining stock (
> The trouble with chip resellers is that it's hard to know which ones are leg$
And then there are the periodic mentions of supposed chip vendors who
ask you what package and what pin count when you ask them for a part
that has never existed except in one version.
/~\ The ASCII
On 10/26/16 7:38 AM, Noel Chiappa wrote:
But DS8641's are available in the 10's of thousands, there's no earthly way
we could use them all on repairs. Yes, when they run out, we'll have a
problem - but I plan to cross than bridge _if_ and when we get to it.
Noel
Actually since about
Guy S.
Thanks saved me the time to say exactly what you said. For all those that
thing designing a driver is a simple thing to do, make your self a
simulated Unibus that is 50 feet long, add around 30 'stubs' load it down
to the max and show me your 'easy to build' drivers signal quality.
On Mon
> From: Philipp Hachtmann
> Very enlightening.
> You're hoarding interface ICs with commercial second thoughts
If you think either Guy, or Dave and I, expect to make much money selling the
QBUS/UNIBUS boards we are working on, you are seriously confused. None of us
are in this as a mo
> On Oct 26, 2016, at 9:18 AM, Christian Gauger-Cosgrove
> wrote:
>
> On 26 October 2016 at 10:02, Philipp Hachtmann wrote:
>> BTW Why isn't there a separate list "ccbusinterfacechip" where those
>> recurring 8881 discussions can be separated from the more interesting stuff?
>>
> The discussi
On 26 October 2016 at 10:02, Philipp Hachtmann wrote:
> BTW Why isn't there a separate list "ccbusinterfacechip" where those
> recurring 8881 discussions can be separated from the more interesting stuff?
>
The discussion is enlightening. It would be nice, however, to
summarize the various conclusi
> On Oct 26, 2016, at 7:02 AM, Philipp Hachtmann wrote:
>
> Hi,
>
> On 10/25/2016 10:49 PM, Guy Sotomayor Jr wrote:
>> Secondary chip marked (only reputable vendors). I currently have ~2500 8641
>> and several 100’s of the other variants. Assuming 100% good parts, I have
>> enough stock to bu
Hi,
On 10/25/2016 10:49 PM, Guy Sotomayor Jr wrote:
Secondary chip marked (only reputable vendors). I currently have ~2500 8641
and several 100’s of the other variants. Assuming 100% good parts, I have
enough stock to build at least 100 unibus boards (total) of various types that I
have planne
> From: Paul Koning
> The trouble with chip resellers is that it's hard to know which ones are
> legit, and which ones are in the fake chip business.
I suspect that the network of major resellers would tend to keep out the
riff-raff. (They don't need the aggro of dealing with the cons
> On Oct 26, 2016, at 9:07 AM, Noel Chiappa wrote:
>
>> ...
>
> So that figure I was given of 30K in stock is probably not from that one
> vendor, but across all of them. But since nobody is using these chips in a
> product (that I know of), I suspect the number is likely to go down only
> slow
> From: allison
> What vendor
I don't recall, would have to look it up; I turned Guy onto them, and he
bought out everything they in stock.
> They have been scarce save though resellers that have NOS parts from
> old stocks and they are not cheap and unpredictable quantities.
Ye
On 10/26/16 7:38 AM, Noel Chiappa wrote:
> From: Guy Sotomayor
> Secondary chip marke[t] (only reputable vendors).
I'm a little more willing than Guy to troll in disreputable waters (I bought
1K DS8641's from a source in Hong Kong), so I have this:
http://ana-3.lcs.mit.edu/~jnc/te
> From: Guy Sotomayor
> Secondary chip marke[t] (only reputable vendors).
I'm a little more willing than Guy to troll in disreputable waters (I bought
1K DS8641's from a source in Hong Kong), so I have this:
http://ana-3.lcs.mit.edu/~jnc/tech/QSIC/TestCardF.jpg
which has a bunch of s
On 10/25/2016 04:24 PM, Guy Sotomayor Jr wrote:
>> On Oct 25, 2016, at 12:40 PM, allison wrote:
>>> Also, I think in a previous email you mentioned that the UNIBUS is 240ohm.
>>> It’s not.
>>> It’s 120ohm.
>> My book says no. Qbus is for sure 120.
>>
> Section 5.2.5 of the PDP-11 UNIBUS spec:
>
On Tue, 25 Oct 2016, Guy Sotomayor Jr wrote:
OK, re-reading the first part of section 5.2.5, it?s pretty clear that the
Unibus is 120-ohm:
A bus terminator is defined as a Unibus element or part of an element containing
a resistive network which connects to the end of a Unibus segment and matche
> On Oct 25, 2016, at 12:40 PM, allison wrote:
>
>>
>> Also, I think in a previous email you mentioned that the UNIBUS is 240ohm.
>> It’s not.
>> It’s 120ohm.
> My book says no. Qbus is for sure 120.
>
OK, re-reading the first part of section 5.2.5, it’s pretty clear that the
Unibus is 120-
> On Oct 25, 2016, at 12:40 PM, allison wrote:
>>
>> Also, I think in a previous email you mentioned that the UNIBUS is 240ohm.
>> It’s not.
>> It’s 120ohm.
> My book says no. Qbus is for sure 120.
>
Section 5.2.5 of the PDP-11 UNIBUS spec:
A Unibus segment must always have a Unibus terminat
On 10/25/16 12:10 PM, Guy Sotomayor Jr wrote:
On Oct 25, 2016, at 8:38 AM, allison wrote:
On 10/25/16 10:02 AM, Guy Sotomayor Jr wrote:
On Oct 24, 2016, at 11:35 PM, ben wrote:
On 10/24/2016 2:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
The voltages are based on TT
On 10/25/2016 03:36 PM, Eric Smith wrote:
On Tue, Oct 25, 2016 at 2:09 PM, Paul Koning wrote:
As for the receiver, it seems that a TI 75140 (adjustable threshold line
receiver) might do the job.
The high-level input current spec on that is max 100uA, which exceeds the
DEC specification.
One
> On Oct 25, 2016, at 4:36 PM, Eric Smith wrote:
>
> On Tue, Oct 25, 2016 at 2:09 PM, Paul Koning wrote:
>
>> As for the receiver, it seems that a TI 75140 (adjustable threshold line
>> receiver) might do the job.
>>
>
> The high-level input current spec on that is max 100uA, which exceeds t
> On Oct 25, 2016, at 1:35 PM, ben wrote:
>
>>
>> If you want to build boards that will work in a small subset of systems
>> that’s
>> find…but don’t advertise it as Unibus compatible. I test the boards I
>> produce
>> in all of my systems (11/20, 11/34, 11/40 and 11/70) and they all use DEC
> On Oct 25, 2016, at 4:31 PM, Guy Sotomayor Jr wrote:
>
>
>> On Oct 25, 2016, at 1:09 PM, Paul Koning wrote:
>>
>>
>>> On Oct 24, 2016, at 4:48 PM, Guy Sotomayor Jr wrote:
>>>
>>>
...
Where do you see the 25 ns spec? I didn't see it (admittedly in a quick
scan).
>>>
>>>
On Tue, Oct 25, 2016 at 2:09 PM, Paul Koning wrote:
> As for the receiver, it seems that a TI 75140 (adjustable threshold line
> receiver) might do the job.
>
The high-level input current spec on that is max 100uA, which exceeds the
DEC specification.
One thing everyone seems to be ignoring is
On 10/25/2016 8:02 AM, Guy Sotomayor Jr wrote:
On Oct 24, 2016, at 11:35 PM, ben wrote:
On 10/24/2016 2:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
The voltages are based on TTL levels. What are the unique voltages?
The QBUS spec from the 1979 Bus Handbook (the U
> On Oct 25, 2016, at 1:09 PM, Paul Koning wrote:
>
>
>> On Oct 24, 2016, at 4:48 PM, Guy Sotomayor Jr wrote:
>>
>>
>>> ...
>>> Where do you see the 25 ns spec? I didn't see it (admittedly in a quick
>>> scan).
>>
>> 5.2.7. It’s discussing the AC loading as a percentage of the risetime
> On Oct 24, 2016, at 4:48 PM, Guy Sotomayor Jr wrote:
>
>
>> ...
>> Where do you see the 25 ns spec? I didn't see it (admittedly in a quick
>> scan).
>
> 5.2.7. It’s discussing the AC loading as a percentage of the risetime (25ns)
> to allow for the
> reflections.
That seems more like a
On 10/25/16 10:02 AM, Guy Sotomayor Jr wrote:
On Oct 24, 2016, at 11:35 PM, ben wrote:
On 10/24/2016 2:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
The voltages are based on TTL levels. What are the unique voltages?
The QBUS spec from the 1979 Bus Handbook (the Unibu
> On Oct 25, 2016, at 8:38 AM, allison wrote:
>
> On 10/25/16 10:02 AM, Guy Sotomayor Jr wrote:
>>> On Oct 24, 2016, at 11:35 PM, ben wrote:
>>>
>>> On 10/24/2016 2:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
> The voltages are based on TTL levels. What
On Tue, Oct 25, 2016 at 2:35 AM, ben wrote:
> But who has the big systems now days?
Me.
> The days of 4K core is long gone.
I have Unibus machines that were 8 or more "system units" (DD11CK
equivalents), and a PDP-11/20 that takes up 3 BA-11 boxes. 60% of it
is 4K core stacks, BTW, just like t
> On Oct 24, 2016, at 11:35 PM, ben wrote:
>
> On 10/24/2016 2:18 PM, David Bridgham wrote:
>> On 10/24/2016 01:37 PM, allison wrote:
>>
>>> The voltages are based on TTL levels. What are the unique voltages?
>>
>> The QBUS spec from the 1979 Bus Handbook (the Unibus levels are the same):
>>
On 10/24/2016 2:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
The voltages are based on TTL levels. What are the unique voltages?
The QBUS spec from the 1979 Bus Handbook (the Unibus levels are the same):
Input low voltage (maximum): 1.3 V
Input high voltage (minimum):
On 10/25/2016 02:35 AM, ben wrote:
> On 10/24/2016 2:18 PM, David Bridgham wrote:
>> On 10/24/2016 01:37 PM, allison wrote:
>>
>>> The voltages are based on TTL levels. What are the unique voltages?
>>
>> The QBUS spec from the 1979 Bus Handbook (the Unibus levels are the
>> same):
>>
>> Input low
On Mon, 24 Oct 2016, Paul Koning wrote:
You need to look at the PDP-11 UNIBUS Design Description document on
Bitsavers. Firstly, in section 4-1, it specifies which chips to use
and recommends not using a whole list of other chips. The only
recommended chips are: 8640, 8641 and 8881.
Sure.
On 10/24/2016 1:18 PM, David Bridgham wrote:
On 10/24/2016 01:37 PM, allison wrote:
The voltages are based on TTL levels. What are the unique voltages?
The QBUS spec from the 1979 Bus Handbook (the Unibus levels are the same):
Input low voltage (maximum): 1.3 V
Input high voltage (minimum):
On 10/24/2016 03:55 PM, David Bridgham wrote:
> On 10/24/2016 12:01 PM, Paul Koning wrote:
>
>> I don't know about the receiver part, but I'd expect that the drivers could
>> very easily be done with a simple transistor circuit.
> Agreed. However ...
>
>> As for slew rates, unless you have antiqu
On 10/24/2016 01:37 PM, allison wrote:
> The voltages are based on TTL levels. What are the unique voltages?
The QBUS spec from the 1979 Bus Handbook (the Unibus levels are the same):
Input low voltage (maximum): 1.3 V
Input high voltage (minimum): 1.7 V
And from the TI datasheet for the 74LS7
> On Oct 24, 2016, at 10:37 AM, allison wrote:
>
> On 10/23/16 2:59 PM, Al Kossow wrote:
>>
>> On 10/23/16 11:50 AM, shad wrote:
>>
>>> The problem is that there aren't open drain bus transceivers, but the
>>> problem could be solved simply using input-only and output-only components,
>>>
On 10/23/16 2:59 PM, Al Kossow wrote:
On 10/23/16 11:50 AM, shad wrote:
The problem is that there aren't open drain bus transceivers, but the
problem could be solved simply using input-only and output-only components,
connecting two in parallel but opposite direction on bidirectional pins.
On 10/23/16 2:50 PM, shad wrote:
Hello,
surely the old transceivers are the most compatible solution, however you
still need to convert the voltages back and forth...
Plus the solution is not the cheaper, and a little uncomfortable too, as
you need to find these old chips, hoping not to buy f
On Mon, Oct 24, 2016 at 4:35 PM, Guy Sotomayor Jr wrote:
> OK, I guess my last email didn’t make it. It appears to me that the rise
> time is set at 25ns.
>
> You need to look at the PDP-11 UNIBUS Design Description document on
> Bitsavers. Firstly,
> in section 4-1, it specifies which chips t
On 10/24/2016 04:30 PM, Paul Koning wrote:
> I don't see any max slew rate spec in the driver specs in the peripherals
> handbook.
For the QBUS from the PDP11 Bus Handbook 1979, page 125:
AC Specifications
Bus driver output pin capacitive load: Not to exceed 10 pF
Propagation delay: Not to exce
> On Oct 24, 2016, at 1:41 PM, Paul Koning wrote:
>
>
>> On Oct 24, 2016, at 4:35 PM, Guy Sotomayor Jr wrote:
>>> ...
>>
>> OK, I guess my last email didn’t make it. It appears to me that the rise
>> time is set at 25ns.
>>
>> You need to look at the PDP-11 UNIBUS Design Description docume
> On Oct 24, 2016, at 4:35 PM, Guy Sotomayor Jr wrote:
>> ...
>
> OK, I guess my last email didn’t make it. It appears to me that the rise
> time is set at 25ns.
>
> You need to look at the PDP-11 UNIBUS Design Description document on
> Bitsavers. Firstly,
> in section 4-1, it specifies whi
> On Oct 24, 2016, at 1:30 PM, Paul Koning wrote:
>
>
>> On Oct 24, 2016, at 3:55 PM, David Bridgham wrote:
>>
>> On 10/24/2016 12:01 PM, Paul Koning wrote:
>>
>>> I don't know about the receiver part, but I'd expect that the drivers could
>>> very easily be done with a simple transistor ci
> On Oct 24, 2016, at 3:55 PM, David Bridgham wrote:
>
> On 10/24/2016 12:01 PM, Paul Koning wrote:
>
>> I don't know about the receiver part, but I'd expect that the drivers could
>> very easily be done with a simple transistor circuit.
>
> Agreed. However ...
>
>> As for slew rates, unles
On 10/24/2016 12:01 PM, Paul Koning wrote:
> I don't know about the receiver part, but I'd expect that the drivers could
> very easily be done with a simple transistor circuit.
Agreed. However ...
> As for slew rates, unless you have antique transistors, that's not going to
> be an issue give
I'm still getting duplicates from cctech: I'm registered to cctalk but for
many messages, a day after it appears via cctalk, the same message shows up
from cctech - this has been going on since the list crash a year or two ago.
It seems to be the messages that were sent to cctech.
It gets annoyi
Forwarded Message
Subject: Re: DEC bus transceivers
Date: Mon, 24 Oct 2016 13:37:14 -0400
From: allison
Reply-To: General Discussion: On-Topic Posts
To: General Discussion: On-Topic Posts
On 10/23/16 2:59 PM, Al Kossow wrote:
>
> On 10/23/16 11:50 AM, shad
having half of this conversation not making it from cctech to cctalk is really
starting to piss me off
Forwarded Message
Subject: Re: DEC bus transceivers
Date: Mon, 24 Oct 2016 13:10:21 -0400
From: allison
Reply-To: General Discussion: On-Topic Posts
To: General Discussion
> On Oct 23, 2016, at 2:50 PM, shad wrote:
>
> ...
> The idea of using bare transistors seems to me too much simple.
> Not that it couldn't work, but it would be almost impossible to satisfy all
> the specifications of the bus in this way... unless you use a more complex
> circuit with preci
> From: David Bridgham
> Just the bus interface takes over half the area of a dual-height board!
In part because the level converters are SMD, and we had to mount them on
(modified) wide DIP carriers to use them in a wire-wrap board.
> I've played around with laying out what might be
On 10/23/2016 04:57 PM, Toby Thain wrote:
> On 2016-10-23 2:50 PM, shad wrote:
>> Hello,
>> surely the old transceivers are the most compatible solution, however
>> you
>> still need to convert the voltages back and forth...
>> Plus the solution is not the cheaper, and a little uncomfortable to
On 10/22/2016 06:40 PM, David Bridgham wrote:
> On 10/22/2016 12:44 PM, shad wrote:
>
>> What kind of bus transceivers did you used for the QSIC, specially
>> because you have
>> to go from 5V open-drain logic to 3.3V logic?
> To add to Noel's answer, here's a picture of our current prototype b
On 2016-10-23 2:50 PM, shad wrote:
Hello,
surely the old transceivers are the most compatible solution, however you
still need to convert the voltages back and forth...
Plus the solution is not the cheaper, and a little uncomfortable too, as
you need to find these old chips, hoping not to buy
On 10/23/16 11:50 AM, shad wrote:
> The problem is that there aren't open drain bus transceivers, but the
> problem could be solved simply using input-only and output-only components,
> connecting two in parallel but opposite direction on bidirectional pins.
>
The reason for using the old
Hello,
surely the old transceivers are the most compatible solution, however you
still need to convert the voltages back and forth...
Plus the solution is not the cheaper, and a little uncomfortable too, as
you need to find these old chips, hoping not to buy fake chinese duplicates
(it happened to
On 10/22/2016 12:44 PM, shad wrote:
> What kind of bus transceivers did you used for the QSIC, specially
> because you have
> to go from 5V open-drain logic to 3.3V logic?
To add to Noel's answer, here's a picture of our current prototype board.
http://pdp10.froghouse.org/qsic/qsic-wirewrap.
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