March 2016 - vcf-midatlantic

examples of non-crystal based clocks in digital computing?
by Herb Johnson 14 Mar '16

14 Mar '16

> Ben Greenfield posted: > > I have one simple specific question, without a simple answer > and general call for examples. > > I’m researching timing clocks used in general purpose digital > computing. I’m starting to think that Ace/Pilot Ace by Alan Turing > is the start of clock based general purpose computers. I’m starting > to conclude the earlier computers were all basically clocked > by the media holding the instructions. My apologies, but I'm a degreed electrical engineer, who first studied computers as digital logic devices and circuits in the mid-1970's. My response is to refute the premises. I don't think the question is simple or specific. It's kind-of specific, but "timing clocks" and "general purpose computers" are not well defined terms in very old digital computing (since Turing is mentioned). I don't think general examples covering several decades of computing will provide "simple" examples and answers. I have a tough time, figuring out pre-1970's mincomputers (much less pre-1960's mainframes) from my Intel 8080 point of view. Digital computers of decades before, say, computers built from integrated circuits, were of all kinds of designs. They are different in fundamental ways. In particular, some operate under a common timing or clock signal, some do not BUT they may have features that are repetitive. A common clock may be needed or may not. Terms like "synchronous" and "asynchronous" and "sequential", are part of the world of computing theory. Things happening one after another are sequential, but may not be synchronous. Some drum-based computers to my knowledge, included their computing registers *on the drum*. One transistor model of the 1960's I know from ownership, had several copies of its registers on the same tracks - why? For faster access. Was there also a clock signal which was ultimately tied to the drum rotation rate? Have to check the manuals, but the drum did much of the work anyway. As for "general purpose" digital computers - there were all kinds of computers several decades ago, many were specific-purpose. Maybe Ben means "programmable" computers, I dunno. I have little idea about what Ben is looking for. But that's OK, there's nothing wrong with creating some assumptions and premises about ancient computing (digital or otherwise), and seeing what one can learn based on those premises. You have to start with what you know, or think you know. I stumble over my own assumptions all the time. But in my own opinion about retrospective looks at very old computing, there's a problem when one assumes modern designs and architectures as a "standard" and then looks back to see where that "standard" fails or breaks down or when it started. For example: for some reason the thread is talking about crystal-controlled clocks versus not. The question wasn't *exact* clocking. A timing fork in a UNIVAC at 1024 Hertz, "sounds" fine to me. A tuning fork (wikipedia) varies by under 100 parts per million per degree C. But a microprocessor can use a variable clock signal from an R/C circuit and work fine. I run an 1802 microcomputer which sometimes uses an R/C circuit clocking down to audio rates - programs run just fine, not precise in time, but slow (and at very low power consumption, microwatts and milliwatts). I prefer to examine ancient computers on their own merits, look at their features on their own terms and on terms immediately contemporary to their times. As a digital engineer I can compare-and-contrast circuits and learn about benefits and limitations, but only in the context of intended use can one pass judgements. and of course, engineers (and techies) often disagree about such judgements. So: it's an interesting question, when put in a general way: what kinds of ancient (or recent) computers did not depend on a common and well-controlled clock signal to synchronize their operations? and how did some operate without it? But for all I know, Ben is asking when computers "first" used a synchronous clock signal for all its computing circuits (whatever that means). I'm not a big fan of "firsts", in any ranking something is always "first", so what? Herb Johnson vintage computing scold -- Herbert R. Johnson, New Jersey USA http://www.retrotechnology.com OR .net

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Re: [vcf-midatlantic] examples of non-crystal based clocks in digital computing?
by Brian L. Stuart 13 Mar '16

13 Mar '16

On Sun, 3/13/16, Evan Koblentz via vcf-midatlantic <vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: >> I’m starting to conclude the earlier computers were all >> basically clocked by the media holding the instructions. Is >> this correct? > > I don’t believe so. ENIAC had a master pulse generator. > > Brian Stuart (on this list) is making his own ENIAC simulator. Thus he'll > have a mich deeper understanding than the rest of us about how the > computer really worked. To follow up on this, one of the 40 racks of the ENIAC is the cycling unit. It's heart is a 100KHz crystal oscillator, but it also has an input and selector switch to be driven from an external oscillator. Every 20 cycles of this main oscillator makes up one addition time and generates a set of 10 clocking signals that are routed around the whole machine to clock all the other units. There's a selector switch to select continuous, one pulse, and one addition modes allowing the operator to single-step either by single cycles of the main oscillator or by single sets of pulses making up one addition time. The cycling unit even has a built-in oscilloscope to display the main clock or any of the 10 signals routed around the machine. IIRC, the cycling unit is one of the units that UPenn has on display in the Moore School building. (Though I may be misremembering and it may be the initiating unit they have.) Generally, if the main storage for the machine was a drum, it made a lot of sense to put the clock on a track or two of the drum and let the drum's motor determine the basic cycle time of the machine. That way you don't have to worry about keeping the internal clock and the drum drive motor synced, and you get your main clock more or less for free. The G-15 we have in the museum works like that. For most other designs, it makes more sense to have a separate clock either based on a crystal or an R/C oscillator. Interestingly, the engineer Harry Huskey was involved with three of the machines mentioned in this discussion, the ENIAC, the Pilot ACE, and the G-15. BLS

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Sunday museum setup report
by Evan Koblentz 13 Mar '16

13 Mar '16

Adam M. and Anthony (not to be confused with Tony) helped me at the museum today. We finished putting (most of) the microcomputers onto shelves, put (most of) the leftover stuff from the old museum that made its way to the new space back into the warehouse, and purchased (most of) the stuff needed to build our workbench. In summary, we got tons of stuff done without actually getting anything "done". :) Back at it next Sunday.

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examples of non-crystal based clocks in digital computing?
by Ben Greenfield 13 Mar '16

13 Mar '16

Hey All, I have one simple specific question, without a simple answer and general call for examples. I’m researching timing clocks used in general purpose digital computing. I’m starting to think that Ace/Pilot Ace by Alan Turing is the start of clock based general purpose computers. I’m starting to conclude the earlier computers were all basically clocked by the media holding the instructions. Is this correct? I’m currently looking for examples of general purpose computers that do not use crystal based clocks. Any thoughts appreciated. Ben

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Re: [vcf-midatlantic] Opinions needed...
by william degnan 13 Mar '16

13 Mar '16

Wait a few weeks. I have found, believe it or not, you have a better chance to get the same selling price if you wait for the person who wins this auction to save a little money so he can buy yours too. I.e. people who pay top dollar for one rare specialized item will buy more than one if given the chance. Bill Degnan twitter: billdeg vintagecomputer.net On Mar 11, 2016 7:37 PM, "Bill Sudbrink via vcf-midatlantic" < vcf-midatlantic(a)lists.vintagecomputerfederation.org> wrote: > I've never sold anything on ebay in my life. I'd rather > not start now but my little "I'M RICH" comment was not > a joke. I have the same AdLib Gold 1000 card in the > original packaging just like the ebay auction. Actually, > not "just like". Mine is the pre-Windows packaging, only > differing by the absence of the "Microsoft Windows" square > in the corner of the package and fewer diskettes in the > box. I've got the user's guide, warrantee registration > card, everything. So, what to do? Should I put mine up > on ebay now and hope to get some benefit from the attention > on the current auction? Should I wait for this one to end > and hope that the "runner up bidders" will still be > interested? Is my example, not being "Microsoft Windowed", > worth more or less than the one on ebay? > > Thanks, > Bill S. > > > >

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Re: [vcf-midatlantic] examples of non-crystal based clocks in digital computing?
by Duane 13 Mar '16

13 Mar '16

From: Ben Greenfield via vcf-midatlantic Sent: Sunday, March 13, 2016 5:32 AM To: vcf-midatlantic Cc: Ben Greenfield Subject: [vcf-midatlantic] examples of non-crystal based clocks in digital computing? Ben, The UNIVAC 1219B, which VCF has in its collection used a pulse circulating around a delay line to generate the master clock phases. The real time clock interrupts came from a 1024 hertz Tuning Fork Oscillator. No crystals. Duane

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Re: [vcf-midatlantic] examples of non-crystal based clocks in digital computing?
by Evan Koblentz 13 Mar '16

13 Mar '16

>> I’m starting to conclude the earlier computers were all basically clocked by the media holding the instructions. Is this correct? I don’t believe so. ENIAC had a master pulse generator. Brian Stuart (on this list) is making his own ENIAC simulator. Thus he'll have a mich deeper understanding than the rest of us about how the computer really worked.

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Update - tomorrow
by Evan Koblentz 12 Mar '16

12 Mar '16

I'll be at the museum again tomorrow with Amigaphile Anthony B. to continue turning the new room into VCF Mid-Atlantic home.

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museum setup report
by Evan Koblentz 12 Mar '16

12 Mar '16

Tony, his friend Ken, Steve A., and I all worked in the new museum today. Tony and Ken painted the short wall "circuit board green" ... Home Depot says it's "sparkling emerald" or something like that, but I disagree. :) Here's a picture: http://snarc.net/wall.jpg. We removed and painted the outlet faceplates. They need another coat. We'll finish that part next time. On the way home I stopped at Home Depot again and bought black outlets to replace the beige ones. Black outlets will blend in, or least they'll look like something electrical is on the wall. Steve and I spent most of our time setting up shelving and computers in the microcomputer exhibit. Definitely not finished it finally looks like an exhibit vs. being all over the place. Here are some pictures (same side of the aisle from each end): http://snarc.net/aisle1.jpg http://snarc.net/aisle2.jpg Ken moved a set of blinds for us from one window to another, so now four of five windows behind the micro exhibit all match. We will see if InfoAge has any other blinds that also match so we can finish the job. Here's a view from the end of the day, looking into the new double doors from the hallway. Still kind of messy inside, but it's much better than last week.

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OT: Academic Article on Teaching Computers to Children
by Jeffrey Brace 12 Mar '16

12 Mar '16

While searching for academic articles for my Master's in Teaching Class: Typical and Atypical Child Development I thought was interesting because it talks about programming LOGO in the 70's and 80's to children. It goes into some history, then talks about modern walks to teach children programming. http://ase.tufts.edu/devtech/publications/JRTE-robot-hokey-pokey.pdf

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