Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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,

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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)

Re: DEC bus transceivers

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 years - a

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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 (and in a c

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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 >>

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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.

Re: DEC bus transceivers

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:

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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,

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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.

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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: >

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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.

Re: DEC bus transceivers

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):

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

> 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 >>>

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers

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

cctech vs cctalk issues / was Re: DEC bus transceivers

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

Fwd: Re: DEC bus transceivers

Forwarded Message Subject: Re: DEC bus transceivers Date: Mon, 24 Oct 2016 13:37:14 -0400 From: allison <ajp...@verizon.net> Reply-To: General Discussion: On-Topic Posts <cct...@classiccmp.org> To: General Discussion: On-Topic Posts <cct...@classiccmp.org> O

Fwd: Re: DEC bus transceivers

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 <ajp...@verizon.net> Reply-To: General Discussion: On-Topic

Re: DEC bus transceivers

> 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

Re: DEC bus transceivers (was Re: Unibus disk controller with modern storage)

> 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

Re: DEC bus transceivers

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

Re: DEC bus transceivers (was Re: Unibus disk controller with modern storage)

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

Re: DEC bus transceivers

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

DEC bus transceivers (was Re: Unibus disk controller with modern storage)

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.