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Honeywell 200 resurrection

I see your point Dwight but these boards drive the lights on the panel which are continuously flashing along with the data stream, so there is no need for them to latch anything. To prevent permanent latching there has to be, as you say, a current source that is continuously pulsing so why not just use an AC source to achieve that? The result would have been that the lights could be powered by just a suitable transformer without the need for a DC PSU, which in the 1960s would not have been a simple device. I estimate that all the lights in the control panel would collectively draw seven amps at fourteen volts, which is say a hundred watts. Why bother with a hundred watt DC PSU when just a transformer would suffice? I am guessing of course but a key aspect of my project, arising from the fact that I don't have a detailed specification of the circuits in the original machine and am having to rework the design myself, is that I am getting an insight into the problems that the original designers faced, especially because I am restricting myself to using only components that they had available back then. Depending on the relative costs of the SCRs and transistors in the 1960s I can see that using an AC supply with SCRs could well have been cheaper than a DC supply with transistors given that all the lights have to do is follow the changes in the data stream. Of course it is possible that the current source was rectified AC to keep the voltage from ever going negative while still pulsing as a result of no smoothing capacitors being included in the PSU. There appear to be a few large diodes on the board as well as the SCRs but apart from clipping the source voltage I can't imagine what their function might be. I'll just have to wait until the unit is delivered to me. I don't know of any online source of the schematic for the 3IDA0 board, hence my sleuthing approach for now.

Of course an SCR actually is effectively two transistors sandwiched together as a four layer device, which is how the latching that you mention works I suppose. I am amused that SCRs are also called thyristors as I still have a couple of thyratrons, the valve, sorry "tube", equivalent from the days before semiconductors.
 
It's interesting in that the gates of the SCRs appear to be AC-coupled, though without seeing the foil side, that's just a guess.

Could the diodes be tunnel diodes? (again, no foil side, so impossible to say)
 
Chuck, I can see what you mean about the AC coupling and wondered about that myself. I have asked the owner to send me a photo of the track side if he has time. Also the panel has a filament test function which lights all the lamps at once, but offhand I don't see how the board might provide that.

The five diodes on the board all appear to have the same part number, so I doubt that they'd all be tunnel diodes even if one or two were.

For now the whole thing is a mystery. Time and FedEx will tell.
 
RobS said:
​ M_T, thanks for that picture but I am concerned about the description accompanying it. Below is an extract from a 1965 Honeywell advertisement which I can vouch is genuine as I have the original magazine page containing it in my collection of H200 ephemera and have included below it the identification of the magazine and issue from the back of the page containing the advertisement.





wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==
​
wAAACH5BAEKAAAALAAAAAABAAEAAAICRAEAOw==
​
Now this was in an advertisement covering the entire series 200 range up to the 4200, so it is just possible that in 1965 it was vapourware and just intended to attract orders for machines not yet available, but the specification of the 120 shown differs from that on the RICM website. I recollect that one of the smaller machines in the 200 series was produced in two forms, one using transistors and the other using microchips, but I assumed that the latter used the same very primitive Honeywell custom chips that I am using to build my replica. As these clearly emulate their transistorised forerunner circuits I assume that they actually were designed by Honeywell. I know that there were foreign versions of the series 200 machines that may have utilised different technology, such as those made by NEC in Japan, so another version of the 120 may have existed but evidently it was already planned if not produced long before Honeywell took over GE. The GE range of machines that Honeywell acquired were distinctly different technically from their own 200 series, so I can't imagine that any GE technology would have been dressed up to look like a series 200 machine. I may be wrong about that, but your description seems unlikely to be the complete story of the H120.

P.S.
I just read on the Computer History Museum website (I got the name right this time Al.) that GE didn't sell its computer division to Honeywell until 1970.
​
Click to expand...

Rob,
I seem to be missing something here. Was there a picture in the gap. If so it seems to have gone. We had a H3200 so they did build some bigger machines. I know there were other H200 series machines around. The first issue of computer weekly makes several references to them.

https://docs.media.bitpipe.com/io_1...461/First-edition-of-Computer-Weekly-1966.pdf

and I know American Express in Brighton also had one. I remember these things as these places were where the jobs were.

There must have been some connection with Japan as the operating system we ran (I think it was MOD400 and was not used in many places) had adaptations for KataKana characters.

And whilst the H200 series was from Honeywell not GE it did end up in at least one L6000 machine as Honeywell offered Series 200 emulation which as far as I know worked by attaching a a series 200 CPU to a L6000 or L66. We briefly considered it when we upgraded to L66 but as the emulation didn't support MOD400 programs we ditched the idea.

There are some control panel and console keyboard close ups of a 200 series in the credits of the "Billion Dollar Brain" some of which was shot at Honeywell Brentford so most images are of real H200's

https://www.youtube.com/watch?v=Eo6fhkWDj-I

and lots of large H200 series shots throughout the film. Well worth a watch....

some stills here

http://www.starringthecomputer.com/feature.html?f=40

and discussion here

https://www.britmovie.co.uk/forum/p...lar-brain-1967-computer-facility-set-location
 
Oh, for heaven's sake! Yes there is a picture in that post and when I go in to edit it I can see it but it doesn't appear in the preview or in the thread any more. My wife said that she thought this site was run by people who understood computers, so why am I having so much trouble with the software on it? Women ask such awkward questions. don't they? I'll try again here.


H120 spec.jpg
 
Yes, if you look at the comments on that item in Starring the Computer you will find that I posted one there a long time ago and I also mention that site on the links page of my own website. I also have the DVD of Billion Dollar Brain as I used images from it to help me compile the CGI model of the control panel on my website. There are very few colour images of the control panel around and the panels that still exist tend to have the wrong buttons on them as they can very easily be popped off and replaced by others. The machine in the film had all the correct buttons. Also one of the labels above the buttons was changed on later panels. On the original panels as shown in the film there was a button marked "Central Clear" but on later machines it was marked "System Clear" I think. No doubt someone thought that the original text implied that it cleared just the CPU when in fact it cleared the status of all peripheral devices centrally, so the replacement text was introduced to avoid any confusion.

By the way, I have now fixed that previous post so that the picture does show. I had to switch to the source code view in the editor and do some patching to correct the problem.
 
g4ugm said:
Rob,
I seem to be missing something here. Was there a picture in the gap. If so it seems to have gone. We had a H3200 so they did build some bigger machines. I know there were other H200 series machines around. The first issue of computer weekly makes several references to them.

https://docs.media.bitpipe.com/io_1...461/First-edition-of-Computer-Weekly-1966.pdf

and I know American Express in Brighton also had one. I remember these things as these places were where the jobs were.
Click to expand...

I've looked at that copy of Computer Weekly and see what you mean. In the seventies American Express in Brighton was our backup site in case of a major failure of our own machine and I actually went there to run some of our software as a trial, but by then we had ourselves replaced our original punched card H200 with one of the larger machines using tapes. Back in the sixties I wouldn't have known what machine they were using.
 
daver2 said:
I am sure the German EDDA3 computer (http://retrocmp.com/articles/edda3-an-early-transistorized-process-computer) has SCRs in the lamp driver circuits. I will have a look tonight for you. I have (most) of the schematics for this machine.

Dave
Click to expand...

Great, the manual is in German. I doubt that my schoolboy German would be up to it although I did just barely pass the "O" level exam. I used to have the complete listing of the Honeywell Easycoder A assembler's own code but seem to have mislaid it on a permanent basis unfortunately. I do however recollect that the very last line of it read "und wenn sie nicht gestorben sind, dann leben sie heute noch" which I now know is the traditional ending to German fairy tales equivalent to "they all lived happily ever after" but with a typically German practical proviso thrown in, not that any of the listing itself was in German. I have no idea why the writer of the code thought that it was a fairy tale unless there were many subsequent changes to the actual code used that were never documented.
 
Fortunately, the card circuit diagrams (not on the website) are all written in the 'schematic' language...

I will have a look at the binär ausgang schematic tonight and see if my memory is correct...

Fortunately, my wife is fluent in German!

Dave
 
m_thompson said:
I thought that I did a good job of researching the 120 console, but it looks like I might need to do some more.

I got most of the information from here: http://www.bitsavers.org/pdf/honeywe...Series_100.pdf
Click to expand...

Ah, it looks like the G-120 from the 100 series and the 120 from the 200 series were different machines. That's the problem with Honeywell, that they bought other companies' lines and ended up with a gaggle of systems that weren't in any way compatible with each other, not even the model numbers. Some time ago I corresponded with a former Honeywell engineer who had worked on the ex-CCC side of the business in a separate department from the series 200 people after the takeover of CCC's machines. There was considerable competition between them about who had the better technology. The Honeywell 316, part of their further development of CCC's series 16 machines, used Honeywell's own tape drives, which involved a very messy interface because of signal and timing incompatibilities. Required to fix a fault in such an interface this chap told me that he set to and purely by luck found the problem and fixed it, which really impressed all concerned, including himself apparently because he had little idea what he was doing.
 
I updated the WWW page to reflect the Honeywell 120 of the 200 series machines instead of the G-120 and used the information from the Datapro report on Bitsavers.

The company that I worked for in the late 70s and early 80s had datacenters in Denver, Dallas, and Houston filled with Series 200 machines connected to lots of Honeywell CRTs.
 
m_thompson said:
I updated the WWW page to reflect the Honeywell 120 of the 200 series machines instead of the G-120 and used the information from the Datapro report on Bitsavers.
Click to expand...

I looked at your revised page and there is a typo near the bottom where it says "The Series 2000 was superseded in 1972 by the Series 2000 machines."

A former Honeywell engineer who worked on the 200 series from the early 1960s onwards has told me that there was never any crossover of technology between Honeywell's own H series and their GE based G series machines. I knew him back in those days and we got in contact again a couple of years ago as a result of my project.

He also tells me that he may have a schematic for the 3IDA0 boards and he'll try to find it in his loft where he keeps all his old Honeywell stuff. "Try" is the operative word as last year he broke his leg in two places and underwent a complex operation to fix it, so consequently he hasn't been able to climb into the loft since then. Ah, how everyday life interferes with the really important stuff that we do here.
 
RobS said:
I looked at your revised page and there is a typo near the bottom where it says "The Series 2000 was superseded in 1972 by the Series 2000 machines."
Click to expand...

Thanks for proofreading the WWW page. Let me know if there is anything else that we should add or change.

One of my prior employer's inhouse field service people in the Dallas office setup a dual-CPU 200. I didn't see any mention of more than one CPU in any of the 200 documentation. Was that a factory supported configuration, or something special?
 
m_thompson said:
One of my prior employer's inhouse field service people in the Dallas office setup a dual-CPU 200. I didn't see any mention of more than one CPU in any of the 200 documentation. Was that a factory supported configuration, or something special?
Click to expand...
I have no idea as I've never heard of such a thing. The CPU had a timesharing arrangement with the peripheral controllers so that they could operate in DMA mode, so I suppose a second CPU could masquerade as a peripheral controller but that wouldn't exactly amount to a full dual processor machine. I'll ask my aforementioned expert with the much repaired leg.
 
m_thompson said:
One of my prior employer's inhouse field service people in the Dallas office setup a dual-CPU 200. I didn't see any mention of more than one CPU in any of the 200 documentation. Was that a factory supported configuration, or something special?
Click to expand...

My friendly expert says that there was never such a thing, so we have no idea what this person actually created.
 
RobS said:
My friendly expert says that there was never such a thing, so we have no idea what this person actually created.
Click to expand...

Interesting. I remember two identical CPUs on one system. I know that it required special in-house developed code in the operating system to use the second CPU.
 
I looked inside of our 120 console. There are no printed circuit boards inside, but can see where four of them were mounted to the hinged rear panel. All of the internal wiring and switches look OK.
 
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