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101090 discussions

by manney＠nwohio.nwohio.com

Sure -- I'm interested. btw, might I (humbly) suggest that anyone offering something for sale include his (her) e-mail address in the message? Then the subsequent hail of offers will stay off the LISTSERV. manney(a)nwohio.com

28 years, 3 months

Firsts

by sinasohn＠ricochet.net

At 10:26 PM 1/16/98 -0500, you wrote: >>Haddock says (now that I'm home) the Compass was early 1982, $6000-8000. > >Forgive me, my ignorance, O Wise One, but what is this Haddock? I think that's the first time anyone's ever called me wise (except, of course, myself, who knew it all along.) 8^) Haddock, Dr. Thomas F., author of "A Collector's Guide to Personal Computers and Pocket Calculators", ISBN # 0-89689-098-8. It's an excellent first go at a refernce book on collectible microcomputers; incomplete, and inconistant, but a good start. (I can't speak for the calculator part.) Prices are not realistic (some too high, others too low) and missing a lot of machines, but good for what it's got. I think I got my copy from amazon (http://www.amazon.com/) but other bookstores (like powell's (http://www.powells.com/) might have it as well.) His PhD, btw, is in physics, and he's also the author of a book on Jag E-type restoration. Go figure.

28 years, 3 months

Cleaning out my storage room...

by manney＠nwohio.nwohio.com

I dibs the 486 and/or the VLB card, if it has drivers. manney(a)nwohio.com

28 years, 3 months

PDP-11/73 -- VT220

by manney＠nwohio.nwohio.com

Have you set the communications protocols correctly? Baud rate, parity, stop bit(s), word size? That's the usual reason for gibberish. manney(a)nwohio.com ---------- > From: classiccmp(a)u.washington.edu > To: Manney > Subject: PDP-11/73 -- VT220 > Date: Sunday, January 18, 1998 2:45 PM > > I picked up a VT220 yesterday, as I was getting tired of using another > computer for a terminal. The question is how do I connect it? I'm > assuming the DB25 on the back of the VT220 is the comm line (especially if > I read the back correctly), I gather the DB9 is for a printer (from what I > found in my web searches last night). > > I took a cable and ran it from the Comm port on the /73 to the Comm port on > the VT220, and get nothing. I then added a Null-Modem adapter and got > gibberish. Does this need some kind of special cable to work? I don't see > any switch settings on the back of terminal or anything. > > Oh, and the VT220 say's it's OK when I power it on. > > Zane > > > | Zane H. Healy | UNIX Systems Adminstrator | > | healyzh(a)ix.netcom.com (primary) | Linux Enthusiast | > | healyzh(a)holonet.net (alternate) | Classic Computer Collector | > +----------------------------------+----------------------------+ > | For Empire of the Petal Throne and Traveller Role Playing, | > | see http://www.dragonfire.net/~healyzh/ | > | For the collecting of Classic Computers with info on them. | > | see http://www.dragonfire.net/~healyzh/museum.html | > >

28 years, 3 months

Firsts

by chemif＠mbox.queen.it

At 03:58 11/01/98, you wrote: Someone At 01:44 PM 1/11/98 -0500, wrote: >>> >First programable calc >>> >>> Then there is the "first solid state electronic calc" which I think goes to >>> the Busicom from Japan that employed the first production run of the intel >>> 4000 chip set: the 4001 (2048 bit ROM), 4002 (320 bit RAM), 4003 (10 bit >>> shift register), and the 4004 (4 bit CPU). That chip set was shipped to >>> Busicom in March 1971 according to Michael S. Malone's "The >Microprocessor: >>> A Biography" ISBN 0-387-94342-0 Then William Donzell added: >>Wang's first (or quite near their first) product was an all electronic >>calculator, introduced in the late 1960s. They are big, but could be >>lugged around. Then Joe: > HP's first calculator, the 9100a, was introduced in 1967 or 68. It had >no ICs, used core memories, and used logic gates made of diodes and >resistors. It did have transistors but they were mainly used as amplifiers >for the core memory. I guess it still qualifies as "solid state".) It was >fully proggramable and used RPN. I have a 9100B with a 1969 date code. > > I believe the Japanese Busicom calculator is even older and dates from >about 1966. Let see if I' m able to go more back: I translate from the URL page of the Pisa University Scientific Instruments Preservation Dept. < http://www.difi.unipi.it/museo/calcolat/miniepc/miniepc.html > Olivetti Programma 101 Olivetti Programma 101 Programma 101 comes introduced in 1965 during the BEMA elecronic show,in New York.It represents the first "desktop calculator" ever constructed in the world. 40.000 exemplary were constructed at the price of 3.200 $ The machine offered the possibility to carry out arithmetical operations in direct way, or of being programmed for the calculation of complex functions. The programs could be stored in magnetic stripes. It was entirely planned and realized in the Olivetti research laboratories of Pregnana, from a group of researchers guided from the Ing. Piergiorgio Perotto, the design was from the Arch. Mario Bellini. Attacment:picture of the machine "olip101.jpg"

28 years, 3 months

ID help (Commie, IBM, Nissho?)

by cgregory＠lrbcg.com

The Vic-1541 was the disk drive with the colors of the Vic-20. These were marketed at about the time of the introduction of the C64 and could be used with either the Vic-20 or the C64. Internally the Vic-1541 and the original beige Commodore 1541 (the one with the pull down door latch) are essentially the same. The later versions of the C-1541 (flip down latch) were changed internally with different drive moters, etc. Functionally they are all the same. Is it worth $10.00 ? The Vic-1541's are somewhat more uncommon that the C-1541's, and are in a little more demand among Commodore collectors for that reason. I would put their value at between $10 and $20. In other words, if I were in San Francisco I probably would have picked it up, but it's not worth shipping across country. Now then, should you happen across one labled "Vic-1540", you had better grab it as they are ultra-rare. I've only heard that they exist, I've never actually seen one. Supposedly they were introduced for a short time before the Vic-1541 and the drive speed is set for the Vic-20, and therefore will not work with the later Commodore machines. Cliff Gregory cgregory(a)lrbcg.com -----Original Message----- From: classiccmp(a)u.washington.edu <classiccmp(a)u.washington.edu> To: Cgregory <Cgregory> Date: Monday, January 19, 1998 5:01 AM Subject: ID help (Commie, IBM, Nissho?) >I know what a 1541 disk drive is, but what about a Vic-1541? Is it worth $10? > >--------------------------------------------------------------------- O- > >Uncle Roger "There is pleasure pure in being mad >roger(a)sinasohn.com that none but madmen know." >Roger Louis Sinasohn & Associates >San Francisco, California http://www.crl.com/~sinasohn/ > >

28 years, 3 months

Transformer theory for computer hackers.

by Philip.Belben＠powertech.co.uk

This would be easier with some diagrams, but I'll do my best. This is not strictly on topic but I think I'd better clear up some of the confusion since I caused it! The equivalent circuit of a transformer is an "ideal transformer" in series with an impedance and in parallel with a magnetising impedance: O---------------+----------UUUUUU----/\/\/\/----)||(-------------O | )||( / Xs Rs )||( O I \ Rm )||( U N / )||( T P | )||( P U ) )||( U T ) Xm )||( T ) )||( | )||( O---------------+-------------------------------)||(-------------O The ideal transformer merely changes voltage. Xs = series reactance (inductive) Rs = series resistance (copper loss - due to resistance of windings) Xm = magnetising reactance Rm = magnetising resistance (iron loss - due to hysteresis of core) There are two things limiting the power you can shove through a transformer. First (and quite easy) is the thermal limit - the current flowing in Rs. In reality, the thermal limit is the current flowing in _any_ winding, which might burn out that winding. Next is the flux in the core. The two windings of the ideal transformer carry equal and opposite ampere-turns, and their flux cancels out. The flux in the core is determined by the current in Xm, which depends on voltage and frequency (remember it's an inductor - more current at lower frequencies) Usually the transformer has a primary winding with a rated voltage (so you don't over-flux it. It also has a VA rating which determines the current (so you don't burn out the windings) If you are trying to kludge things, there are some special cases to worry about. 1. 50Hz MAINS. If your transformer is designed for 60Hz mains and you want to use it at 50Hz, the lower frequency will meaan that Xm is lower. (X=2*PI*f*L). The magnetising impedance will draw more current, and the flux in the core will be higher. From a practical point of view, this means that the rated VOLTAGE must be lower. For example if it is designed for 240V, 60Hz, at 50Hz the rating is 200V. This is called DERATING. Since the rated voltage is lower, and the rated current is the same (excessive current will melt copper whatever the voltage), the VA rating is also less. Most small commercial transformers are designed for 50Hz anyway, so this shouldn't be a problem. However (following the discussion of mainframes and things) most [North American] medium to large power transformers are not! (Medium > 5kVA I suppose. Large probably > 50 kVA. Hard to say - in my job I regularly deal (at least on paper) with 500000kVA transformers) 2. HOME MADE AUTOTRANSFORMERS. An autotransformer has the low voltage end of one winding connected to the high voltage end of another. This saves copper, reduces core size, etc. It is often used for converting between mains voltages and is at its best around the 2:1 voltage ratio. Many small transformers are made with two primary windings, each rated at 120V or thereabouts. The idea is to connect them in series for 240V operation and in parallel for 120V. A trick I mentioned a few days ago is to wire them together as an autotransformer (Windings are W1 and W2 in the diagram: +---------------O | )|| W1 )|| )|| O-----------------+|| )|| IN- W2 )|| PUT )|| | O-----------------+---------------O Call the VA rating of the transformer V*I, where V is the voltage rating of the windings in series (usually 240V) and I is the current that flows in each winding. On the HV (higher voltage) side, we want V and I. On the LV side we must therefore provide V/2 and 2I. (Assuming an ideal transformer for the moment) Now each winding is rated at V/2, so energising one at this voltage is not a problem. But each winding is only rated at I, so what do you do with the 2I you have to supply? 2I must flow in at the junction of the two windings, and I must flow out at the HV terminal. It is easy to see that I will flow through W1; the rest of the current entering at the junction must flow through W2. Simple arithmetic tells you that each winding carries a current of I; the ampere turns are equal and opposite, so the transformer will work. However, once you add the imperfections, you do start to get a few problems. I'd have to do some serious calcs to find out exactly how Zs (= Rs + i*Xs) and Zm affect it, but you may have to take a VA rating 10% or so lower than nameplate. Which is not much of a loss. You also have a regulation problem. Most small transformers have extra turns on the secondary to compensate for the voltage drop across Zs. Here you are only using the primary, so you don't get this. Expect a voltage drop (proportional to load current, of course) of about 10% to 20% (less for larger transformers) at full load. So, in response to Tony's comment, the transformer won't mind if you use it almost up to nameplate rating - but you may not get as many volts out as you expected. Using a transformer at 30% of nameplate rating is as good a way as any to avoid this! In response to (I forget your name - sorry!) I hope this has explained what I was getting at. Finally, SCOTT CONNECTION etc. Someone yesterday(?) tried to perpetuate one of the myths about the Scott transformer, which is used in converting balanced 2-phase to 3-phase power. If you have two phases at 90 deg to each other, you have a balanced 2-phase supply. This is very rare! There will usually be 3 wires - two phases and neutral - and the phase to phase voltage will be about 1.41 times the phase to neutral voltage. The scott transformer (actually two single phase transformers) converts this to and from 3 phase. Most US domestic supplies (and a few UK rural supplies to farms and things) have two phases at 180 deg to each other - phase to phase voltage is twice phase to neutral voltage. THERE IS NO TRANSFORMER THAT WILL GIVE YOU THREE PHASE FROM SUCH A SUPPLY. You need preferably a motor-generator or dynamotor (motor-generator sharing a common rotor winding). As mentioned previously, an induction motor with suitable capacitors and things will do this quite well up to a point. Electronic converters exist and are getting cheaper all the time... Finally, you may have two of the phases of a three-phase system. If you have three wires - two phases and neutral - there is a transformer that will derive balanced 3-phase from this. If not, you're in the same position as with a single phase or unbalanced 2-phase (which is actually single phase centre tapped to earth) supply. If anyone STILL doesn't understand what's going on, ask privately. Who knows? If I get very many questions, I may be posting "3 phase ac theory for computer hackers" before long... Philip. <><><><><><><><><><><><><><> Philip Belben <><><><><><><><><><><><><><> Bloedem Volke unverstaendlich treiben wir des Lebens Spiel. Grade das, was unabwendlich fruchtet unserm Spott als Ziel. Magst es Kinder-Rache nennen an des Daseins tiefem Ernst; Wirst das Leben besser kennen, wenn du uns verstehen lernst. Poem by Christian Morgenstern - Message by Philip.Belben(a)powertech.co.uk

28 years, 3 months

System/34

by Philip.Belben＠powertech.co.uk

Someone asked about power requirements for IBM S/34. All I can say is it's less than 7 kVA (ours was plugged into 30A, 240V single phase circuit. The other one at IBM Bristol was plugged into a 3-phase 415V socket but I don't know whether it used all 3 phases) If there's one going begging, I want it as long as (a) it's within 200mi of Coalville, England and (b) it can wait a week or three while I get my truck back on the road. Philip

28 years, 3 months

Toronto-area comp museums ?

by kstumpf＠unusual.on.ca

Did any one ever reply? I believe I'm the chap in the K-W area. We once had Canada's first computer museum, but it has since closed. Have you seen our web site? www.sentex.net/~ccmuseum. Please let me know what I can do to help you. Yours in good faith.

28 years, 3 months

One question was: Re: Cleaning out my storage room...

by jpero＠cgo.wave.ca

Oh, About lunchbox, I nearly forgot, To anyone who knows the Canadian-USA border well, could anyone tell me what is proper proccedures to let border guys know that I'm ridding of this lunchbox? It has the small yellow serial label that border person stuck on my lunchbox when I was travelling to visit my friend. The empty lunchbox was originally privately brought used by mail from a person in USA during last summer. Thanks! Jason D.

28 years, 3 months

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