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rvaneynd
December 14th, 2011, 03:39 AM
Hi,

Have been given a memory module of a Burroughs B6700 (see photos attached).
Does anybody know how much memory this is?

I believe it is a 50Kb module, but I am not sure.

It says DataProducts Assy 716303-1 it is 3 Wire Core Memory.

73237324

Thanks,
Raoul

nigwil
December 14th, 2011, 06:19 PM
Hi Raoul,

A few details which might help to decipher the board:

B6700 had 52-bit words (48-bits + 3 tag bits + 1 parity bit) and a maximum addressing capacity of 1MiW (1 048 576 locations, 6Mbytes) via 20-bits of address which was split into 14-bits to select a word (16KW range) and 6 bits to select a memory module (64 modules).

Do you have any more information about the machine this memory module came from? was the B6700 recently scrapped and if so where was it located? are there any pictures of the original machine?

cheers.

rvaneynd
December 15th, 2011, 04:36 AM
Thank you for the response.

I do not have much more information except for.
The B6700 was scrapped over 30 years ago, I think.

The modules came out of the B6700 that was installed at Technical University in Eindhoven, Holland.
My dad used to study and work there and when they scrapped it, he took the boards out and framed them as they make for some great Technology Art.

Now he has passed them on to me and I am just curious about the memory capacity.

Raoul.

billdeg
December 17th, 2011, 05:43 PM
it was from late 60's right...early virtual memory system?

nigwil
December 17th, 2011, 10:04 PM
Burroughs B6700 is from 1971/1972, although it was based on the B6500 which was 1968/1969. It had segment-based virtual memory rather than page-based virtual memory. Segments could be code or data (down to array level granularity).

nigwil
December 18th, 2011, 07:02 PM
My guess, assuming it is a single core plane, based on what look to be address decoders on the edges, this may be 1KW of memory, that is 1024 x 48 bits, so a total of 48Kbits or 6Kbytes, which would match your "...a 50Kb module" statement.

If you can place the board on an image scanner and get a close up picture we might be able to identify the chips involved and other features which might be more conclusive.

jim s
December 21st, 2011, 06:59 PM
My guess, assuming it is a single core plane, based on what look to be address decoders on the edges, this may be 1KW of memory, that is 1024 x 48 bits, so a total of 48Kbits or 6Kbytes, which would match your "...a 50Kb module" statement.

If you can place the board on an image scanner and get a close up picture we might be able to identify the chips involved and other features which might be more conclusive.

It's been a long time... like 30 years since I saw one, but that looks like half a a "planar core" memory module from a B6700. It's the sense amp part, the actual core was on a second board bolted to those standoffs and connected by all of those pins on the edges. This was the last core memory Burroughs used before going to chip memory. Each one of these assemblies was 20 bits of a system word, and 3 boards made a complete 60 bit word. The extra bits were used to correct single bit errors on the fly, and detect multiple bit errors. I'm thinking they were 32K x 20 bits each. Anyway, the 6700 could have 6MB of main memory. Using this stuff, that took 4 cabinets about 4 ft wide, maybe 6 tall, and 2 deep. ;-)

They weren't supposed to be field repairable, but I did fix one that had a bad sense amp.

jim s
December 21st, 2011, 07:19 PM
oops... I missed the second picture. I'm pretty sure that's a planar core module.

Chuck(G)
December 21st, 2011, 07:29 PM
It's been a long time, but what little I can recall from my RFQ work (know the competition), wasn't the B6700 used as a frontend to the BSP?

jim s
December 22nd, 2011, 06:26 AM
It's been a long time, but what little I can recall from my RFQ work (know the competition), wasn't the B6700 used as a frontend to the BSP?

I remember hearing about the Burroughs Scientific Processor back then, but I think it used a 7700 or 7800 as manager. I wonder if any of them were actually deployed? I know I never saw one... but that only covers maybe a half dozen 6700s or 7700s.

Chuck(G)
December 22nd, 2011, 10:14 AM
I don't know how many BSPs were actually deployed, but supercomputers were never a quantity seller. We had a couple of bids out against BSP proposals, but neither we (CDC) nor Burroughs won. The TI ASC was another competitor back then--I don't know if they ever sold any. Cray picked up the lion's share of sales right about then (early 70s).

It was an awkward time for the market--the world was moving to semiconductor memory and at the same time, moving toward ICs from discretes--and ICs were getting faster very quickly. Manufacturers were trying to jump on the bandwagon as fast as they could (it took a lot of time to design a new machine) and a lot of things turned out badly--I recall the Honeywell completely redesigned one of their older models to use ECL IC technology and found that the result didn't run any faster, but did eat more power.

jim s
December 22nd, 2011, 12:11 PM
I don't know how many BSPs were actually deployed, but supercomputers were never a quantity seller. We had a couple of bids out against BSP proposals, but neither we (CDC) nor Burroughs won. The TI ASC was another competitor back then--I don't know if they ever sold any. Cray picked up the lion's share of sales right about then (early 70s).


The good old days. ;-) Back when I was a student at Michigan State, the computer lab had a CDC 6500 and a 3600, at least I think those were the model numbers. Not that they would let any of us undergrads near it, just the observation room to see the blinkenlights.

Chuck(G)
December 22nd, 2011, 02:49 PM
I don't recall much about the 3000-series, only that they were 24- and 48-bit machines related somewhat to the 1604; most of my work was in 6000/Cyber 70 before I went onto the STAR-100 project. The 6500 was pretty popular with universities; I think Purdue also had one as well as Colorado. Basically two 6400s sharing memory and PPs. There was also a 6700--6600 and 6400 CPUs in the same box. I'd heard that a 6500 cost substantially less than a 6600, but never verified that.

All you needed in addition to the box was an MG set (208V-3-phase-400Hz), the usual HVAC for peripherals and a chilled water supply for the CPUs. Aren't you glad that you're not collecting those? :)

nigwil
December 22nd, 2011, 06:21 PM
... Each one of these assemblies was 20 bits of a system word, and 3 boards made a complete 60 bit word. The extra bits were used to correct single bit errors on the fly, and detect multiple bit errors. I'm thinking they were 32K x 20 bits each.
I've never heard of it described this way, do you have a reference for the memory layout you describe which suggests that the B6700 had 60-bit memory words?

I am using this reference where it states:


B6700 Reference Manual (http://bitsavers.org/pdf/burroughs/B6500_6700/1058633_B6700_RefMan_May72.pdf),
page 1-8 in the section on "Memory Words":

Each memory word contains 48 information bits, three control bits, and a parity bit. for a total of 52-bits per addressable word.

I also read in the Burroughs B6700 Handbook Volume I Hardware, in section 8 (Interface Cables) which details the memory subsystem I see just 52-bus lines described connecting the CPU to the memory subsystem.

jim s
December 22nd, 2011, 07:49 PM
I've never heard of it described this way, do you have a reference for the memory layout you describe which suggests that the B6700 had 60-bit memory words?

I am using this reference where it states:


B6700 Reference Manual (http://bitsavers.org/pdf/burroughs/B6500_6700/1058633_B6700_RefMan_May72.pdf),
page 1-8 in the section on "Memory Words":

Each memory word contains 48 information bits, three control bits, and a parity bit. for a total of 52-bits per addressable word.

I also read in the Burroughs B6700 Handbook Volume I Hardware, in section 8 (Interface Cables) which details the memory subsystem I see just 52-bus lines described connecting the CPU to the memory subsystem.

I don't have any of my old reference books, I'm just going on my own memory from back then. I was a field service engineer on the 6700. The system did have a 52 bit word - 48 data bits, 3 tag and one parity. For this particular memory system, there were actually 60 bits per word. The other 8 bits never left the memory controller. The memory controller generated an 8-bit code in hardware that was determined by the other 52 bits. On reading, it was compared and could determine if there was a single bit error or multiple bit error. If it was single, the error bit number could be determined and flipped. Kinda neat, unless that part of the controller failed.

jim s
December 22nd, 2011, 08:03 PM
All you needed in addition to the box was an MG set (208V-3-phase-400Hz), the usual HVAC for peripherals and a chilled water supply for the CPUs. Aren't you glad that you're not collecting those? :)

I seem to recall the B6700 used enough power for several suburban homes. The AC power mod ran on three phase, although I don't remember the voltage. Each of the mainframe boxes had a 400A or 600A logic supply with the odd voltages of 4.75 and -2v. Handy way to heat one's house. ;-)

Chuck(G)
December 22nd, 2011, 08:18 PM
I seem to recall the B6700 used enough power for several suburban homes. The AC power mod ran on three phase, although I don't remember the voltage. Each of the mainframe boxes had a 400A or 600A logic supply with the odd voltages of 4.75 and -2v. Handy way to heat one's house. ;-)

That's pretty close to the truth. In January, 1974, I had to make a trip from Sunnyvale to St. Paul/Arden Hills. This was the height of the Arab oil embargo. Everything was cold--including my room at the Ramada. At CDC, there was ice on the inside of the windows of the offices. People were wearing three sweaters at work.

I holed up with my work in the STAR machine room at ADL between a couple SBUs. Nice and toasty. The next evening, I brought a pillow and slept on the floor. It must have been the only place in the Twin Cities that was a comfy 74 degrees. :)

MikeS
December 22nd, 2011, 08:30 PM
I seem to recall the B6700 used enough power for several suburban homes. ...Handy way to heat one's house. ;-)I can believe it; when I worked with Burroughs they had one for a while in the DP room where I would occasionally use its smaller sibling, a 2700, and it was a biggie all right.

The CPU & memory cabinets alone took one entire wall of a fairly large room, and it had the most impressive panel of blinkenlights I've ever seen; it was in house for a couple of months being tested and set up for the Metro Toronto police department, and when idle it displayed the MTP crest on its panel of lights which ISTR was about 3 feet square; those bulbs alone probably would have heated one or two small rooms...

7406

As a matter of fact that's probably yours in the picture, Nigel.

nigwil
December 22nd, 2011, 08:46 PM
Each of the mainframe boxes had a 400A or 600A logic supply with the odd voltages of 4.75 and -2v. Handy way to heat one's house. ;-)
The B6700 hardware manual lists several other voltages too: for the core-memory system there are +1V, -50V, +63V and +37V. In another part of the CPU/DCP system there are also +12V and -12V - the power supplies must have been quite complex to supply so many different voltages.

Burroughs appear to have their own logic integrated circuits listed as CTuL (Complimentary Transistor Micro Logic), they were positive logic, "true" was +2.5V and "false" was -0.5V


Jim: do you happen to remember what was special about the B6748 "restricted model"? it is not listed in the reference manual I have but I found another reference to it in Doran's book.

nigwil
December 22nd, 2011, 08:54 PM
As a matter of fact that's probably yours in the picture, Nigel.
Well as that picture came from my website and yes it is the UTAS B6700 :-)

MikeS
December 22nd, 2011, 10:25 PM
Well as that picture came from my website and yes it is the UTAS B6700 :-)Duh! ;-)

How's the System 3 coming along?

jim s
December 23rd, 2011, 06:36 AM
The CPU & memory cabinets alone took one entire wall of a fairly large room, and it had the most impressive panel of blinkenlights I've ever seen; it was in house for a couple of months being tested and set up for the Metro Toronto police department, and when idle it displayed the MTP crest on its panel of lights which ISTR was about 3 feet square; those bulbs alone probably would have heated one or two small rooms...

Yeah, that was the big thing for the software guys to recompile the MCP and put the company logo in the idle loop. Mine said "AC" most of the time. I remember one time they were upgrading the MCP and wanted it to be obvious they were on the new vesion. So they put the logo in "negative video". I was not happy ;-) being the one who had to change the bulbs.
That was a large 6700, we had three CPUs 2 IOs and 4 DCPS, at max. After they got the 7700 the 6700 became the development system, and we reduced it down to a single CPU.

jim s
December 23rd, 2011, 06:50 AM
The B6700 hardware manual lists several other voltages too: for the core-memory system there are +1V, -50V, +63V and +37V. In another part of the CPU/DCP system there are also +12V and -12V - the power supplies must have been quite complex to supply so many different voltages.

Burroughs appear to have their own logic integrated circuits listed as CTuL (Complimentary Transistor Micro Logic), they were positive logic, "true" was +2.5V and "false" was -0.5V


Jim: do you happen to remember what was special about the B6748 "restricted model"? it is not listed in the reference manual I have but I found another reference to it in Doran's book.

Sorry, I never heard of the B6748.

Those power supplies were distributed around the system. The AC module converted the input power to DC and routed it to each cabinet where the switching supplies there generated the needed voltages for each cabinet. The 4.75,-2 was one supply, +-12 another. Some of the newer cabinets were independently powered like the DCP and maybe even this particular memory subsystem.

http://img45.imageshack.us/img45/5293/b6700mb1.th.jpg (http://imageshack.us/photo/my-images/45/b6700mb1.jpg/)
I believe this was the demo system at Burroughs WHQ in Detroit

nigwil
December 24th, 2011, 12:34 AM
How's the System 3 coming along?
2012 or bust!

I'm running out of excuses, but for 2012 I want to get the Cromemco System 3 (Cromix), LDP-88 (UCSD p-System), and PDP-8/E (EduSystem) functional.

nigwil
December 24th, 2011, 12:35 AM
http://img45.imageshack.us/img45/5293/b6700mb1.th.jpg (http://imageshack.us/photo/my-images/45/b6700mb1.jpg/)
I believe this was the demo system at Burroughs WHQ in Detroit
Jim - can I use this picture on my website please? it is particularly interesting as it shows a dual CPU configuration.

billdeg
December 24th, 2011, 07:23 AM
2012 or bust!

I'm running out of excuses, but for 2012 I want to get the Cromemco System 3 (Cromix), LDP-88 (UCSD p-System), and PDP-8/E (EduSystem) functional.

I noticed on my System 3 that some of the large power supply caps have leakage, need to be replaced. It's on my 2012 list too...good luck to you.

jim s
December 24th, 2011, 07:51 AM
Jim - can I use this picture on my website please? it is particularly interesting as it shows a dual CPU configuration.

It's OK by me, but I guess it belongs to Unisys... It was from some sort of sales package I believe. Since it was essentially advertising, I don't think they'd mind. ;-)

It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.

nigwil
December 24th, 2011, 12:55 PM
It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.

MikeS
December 24th, 2011, 01:28 PM
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.Definitely bigger than the one we had...

Are those TD800s? I sold mine long ago, but still have a keyboard somewhere; should use that for something.

Nige, did you ever hear any more from the fellow in CA with the TD700? Wonder what happened to it.

Sorry for hijacking the thread BTW, but BBM comes up so rarely...

jim s
December 24th, 2011, 08:52 PM
But was it possible to have both displays connected to the same CPU? I guessed it was dual CPU since both are displaying the idle MCP "B"urroughs light-pattern so I assumed two different CPUs.

It's been such a long time... but I'd guess both panels could be on the same CPU. Anyway, for a demo system, it might be possible for all the CPUs to be in the idle loop. No telling what the configuration of that system was.

jim s
December 24th, 2011, 09:00 PM
Definitely bigger than the one we had...

Are those TD800s? I sold mine long ago, but still have a keyboard somewhere; should use that for something.



Yeah, those are TD800 displays. The 830 was about half that deep. Interesting thing about those... the monitor part of the terminal was an OEM assembly. It was connected to the logic cage via a BNC connector inside. I really messed with the sales guy by taking that off on my scrapped unit and connecting it to a VCR. ;-) I used it for a couple years on my homebrew Z80 along with the keyboard.. then it moved to the Atari 800 until I could afford a color monitor.

rvaneynd
February 2nd, 2012, 09:14 AM
It's great to see a couple of pictures creating this discussion.
In the mean time I have received a few more boards of the B6700, which I will post in the next couple of days.

But also a boards of a Cromemco machine (1 memory and 2 IO). Also pictures of these will be posted.

I will see if I can put the big boards on a scanner to get more details on chips etc.

rvaneynd
February 2nd, 2012, 09:35 AM
77537749775077517752

A bit quicker then expected.
3 x Burroughs 6700 - No idea what the cards are.
2 x Cromemco (1 x memory, 1 x IO).

Raoul.

MikeS
February 2nd, 2012, 01:42 PM
While we're posting Burroughs pictures, here's the operator console from a B2700; not quite the same as the 6700 ;-)

I even have a picture of myself operating this 2700 in my Burroughs days somewhere; will have to dig for that one of these days...

(As it happens I also have piles of Cromemco boards, systems & manuals from my days as a Cromemco sub-dealer...)

7757

Edit: Wow, that's an old picture; I haven't smoked in years ;-)

jim s
February 23rd, 2012, 08:04 AM
I think that first B6700 card is part of the memory buss interface. That small white tag near the 20 pin edge connector lists the card slot where it belongs. My memory may be fooling me, but I think the first letter being "B" means it went in the "multiplexor", otherwise known as the I/O processor.

nigwil
August 28th, 2015, 07:06 PM
It has dual maintenance displays... I never really noticed that before. That wasn't necessary for a dual CPU configuration. The panel could be switched to any CPU or I/O processor.

Reviving this very old thread, I found out from my friend PK, that this was the "failsoft" model of the B6700 that was introduced around November 1972, this was the idea of duplicate-everything so it would keep running no matter what.

Details here:
http://www.retrocomputingtasmania.com/home/projects/burroughs-b6700-mainframe/gallery#TOC-Burroughs-FailSoft-models

jim s
December 15th, 2015, 04:09 PM
Duplicate parts can bite you though... I had a 6700 that had a multiplexor problem... So the plan was to reconfigure to make the B mpx the master and take the failed A mpx ofline for repair. But we didn't realize the B mpx had it's own problem... the time-of-day register had a stuck bit down near the bottom and was running about 4 times faster than normal. Normally, the system uses the A mpx's TOD... By making B the A mpx the system time ran up into the next day before anyone realized it. They had to shut down and let the real world catch up with the computer. ;-) Funny now, 35 years later, but embarassing then...

cruff
December 15th, 2015, 06:05 PM
Unisys is making available a free for hobbyists/personal use version of the Clearpath MCP Express software (only runs on Windows) that is the successor to the B6700 era machines. It looks pretty complete from the datasheet. The license has to be renewed yearly. Almost makes me want to setup a Windows box to run it.

http://www.unisys.com/offerings/high-end-servers/clearpath-forward-systems/clearpath-mcp-software/clearpath-mcp-express

nigwil
December 16th, 2015, 12:51 AM
...Funny now, 35 years later, but embarassing then...

What a great story! do you have any photographs from that era you can share?

jim s
December 16th, 2015, 07:05 AM
What a great story! do you have any photographs from that era you can share?

I'm afraid not. My particular customer was a bit paranoid about cameras on site. Probably no more than any other company, but the one time I came to work with my camera, I had to go back and leave it in the car.

jim s
December 19th, 2015, 08:19 AM
Unisys is making available a free for hobbyists/personal use version of the Clearpath MCP Express software (only runs on Windows) that is the successor to the B6700 era machines.

Much as I like the idea of a 6700 emulator- either in software like this, or an FPGA core for something like the Replay board, I can't figure out what I'd use it for. It might be fun to run a CANDE session and play the old Star Trek game that we renamed FECPUTEST to cover for it ;-) if I still had a machine readable copy.

tingo
December 22nd, 2015, 04:48 PM
Unisys is making available a free for hobbyists/personal use version of the Clearpath MCP Express software (only runs on Windows) that is the successor to the B6700 era machines. It looks pretty complete from the datasheet. The license has to be renewed yearly. Almost makes me want to setup a Windows box to run it.

I wonder if it would run in WINE (http://winehq.com/) instead of VirtualBox or VMware??

snuci
December 22nd, 2015, 05:36 PM
Here was our B6700 for nostalgia.

28474

Large pic here (http://vintagecomputer.ca/wp-content/uploads/2015/01/B6700-large.jpg).

I think we have two memory modules for it at work that have multiple core memory boards in an aluminum case... but I can't lift them.

Chuck(G)
December 22nd, 2015, 07:35 PM
Upgrade the model to a B7800, add a BSP and you might have something that comes close to the power of a 10 year old PC... :)

I've been there too. I remember the hubbub about the BSP and the TI ASC.

jim s
December 23rd, 2015, 08:37 AM
Here was our B6700 for nostalgia.



Those look like Conrac terminals on the console. Back when I installed a 6700, there was a shortage of the newer TD terminals. I think it was something about the factory switching over from TD820s to TD830s. So they sent us all the Conracs they could find and I had to make enough of them work so the programmers could port the software from the IBM 360 we were replacing. I used to have to go over there with a rubber mallet to tap the cards back into their slots. The thing actually predated chip memory for the screen. There was a metal box in the bottom that held a "magneto restrictive delay line". Basically, a spiral of wire with coils at either end. Screen data would pulse the input side, and a physical distortion would ripple down the wire and induce a current in the output coil. There was a tension adjustment screw on there to set the propagation time on the wire.... so yeah I used a screwdriver to adjust the memory.
Another bit of trivia.... the thing also predated ROMs for character sets. One of the circuit boards contained a huge array of discrete diodes to form the character set.
I hated those things. ;-)