test-drb

test-drb@ccmp.vtda.org

101090 discussions

by Philip.Belben＠pgen.com

Jim Willing: > I've added a fairly complete Tektronix 4054 graphics computer system to the > collection. Along with it came a hard copy unit, external tape drive, a > rather large flat bed plotter, and a full set of docs and tapes! You. Lucky. Beggar. (Green with envy) Philip. (sorry there's not much content in this message, but I had to get it off my chest. More and more 4050 series coming out of the woodwork! Keep up the good work!)

26 years, 7 months

How scarce (valuable) is core for the PDP-8?

by Philip.Belben＠pgen.com

><My first thought was something like a small compass near each bit. I want ><to avoid lights since I think they are less engaging, less an indicator ><that something has happened. Ideally this should be an attractive looking ><toy, that sparks curiousity. > > The ferrite would not show enough external field change to be a reliable > indicator. However when the wires were driven they indeed would! OK, how about it. Put a ring of compasses around the wire with needles strongly enough magnetised that they will stay pointing N-S around the ring regardless of the Earth's field. Can you then flip them with a current? A very good visual demonstration of how core works! Philip. BTW Siemens make some torroidal cores down to 1mm thick ferrite, slightly larger in other materials. RS Components stock some - http://rswww.com/ and go in through the catalogue: "Electronics", "Transformers/Inductors/Ferrites", "Ferrites", "Torroids" (sic). There are even data sheets but I didn't manage to download them.

26 years, 7 months

PC question

by allisonp＠world.std.com

<Yesterday, at the KS10 move, I came away with two IBM PCs, but I <don't know enough about them to know if they are the AT or XT <models... they both have a 5.25" floppy and a hard drive, and <both have color monitors. One was a 5150 (xt) the other was a 5170 (also XT) If all fails look at the cpu: XT 8088 or 8086 AT 80286 or later Allison

26 years, 7 months

Powerlines

by Philip.Belben＠pgen.com

I'm not sure whether this was satisfactorily cleared up. Anyway, the message was still on my list of Classiccmp mails to be answered when I finally caught up with reading them this pm. >> > Realy 234V (strange) and 180 degree ? Where do you know ? By definition ? >> > Just remember, if you tap between 2 phases of a 3~ signal you still get >> > a perfect sinus and you can't decide if it is a single phase or part of >> > a 3 phase signal. Ok, I'm always learning new things on this earth :9 >> > The numbers just saemed to fit well. >> I'm sure the power company has a legal obligation to keep the voltage >> within a certain range of values. Although, I don't know exactly what that >> range is. I think 117 is probably the optimal value for each of the legs >> giving 234 for the total. I've heard it referred to as 110, 115, 117, and >> 120. Since the actual voltage varies any of these could be correct. > > Anybody out there knowing the US regulations ? AFAIR somewhen in the > late 70s the acording definitions have been worldewide standardized > on 115V/200V and 230/400V - the intention was to allow manufacturers > (especialy the ones for power transmission systems) to develop more > efiecently and to lower building costs, since within the lower power > range (up to some MW) designs could be standardized on a simple level. >> Since it is a simple transformer, the phases are 180 degrees out of phase >> (by definition). That's assuming a balanced resistive load. Of course, that >> could change under a heavy inductive or capacitive load but, that's an >> extreme and won't normally present a problem. > > Still not an argument against 2 phases from an 3~ signal. 1. Voltage The voltage will be declared by the supply company to be some value +/- some tolerance. This will usually be according to a national standard. The transformer will usually have a higher voltage on its rating plate - if the nominal voltage is 115 or 117 volts, the transformer may be rated at 120V. People near the transformer will get 120V, people at the far end of the cable will get 110V. My house is very near the transformer so I get 248V on a nominal 230V supply (NB when it was nominally 240V I got 248V. Nobody has adjusted the transformer...) 2. Phase. As I understand it the usual practice in the US is take _either_ a phase and earth (neutral) _or_ two phases of the HV supply and feed a single phase transformer from this. The LV side of the transformer is (say) 240V with a centre tap. The centre tap is earthed and provides the neutral connection, the outer two taps are then both hot at 120V, 180 degrees apart. This is true _even if_ the primary (HV winding) is connected between two phases of the HV 3-phase system. In the UK the usual practice is to connect all 3 phases of the HV (almost invariably 11kV phase to phase) to a delta-star 3-phase transformer. The secondary, the star-connected winding provides 3 phases and neutral. Neutral is earthed at the transformer. Protective earth can be provided by _either_ a separate wire from the main earth at the transformer _or_ an earthing electrode at each customer's site _or_ the neutral is earthed at a large number of points on the system and the customer's protective earth is bonded to neutral at the point of entry of the supply. In all cases the customer sees 240V line to neutral; if he gets more than one line (hot) connection, they will be 120 degrees apart. In remote locations, only 2 phases of the 11kV system are taken to the site. Small loads get a single phase 11kV/250V transformer with one end of the LV earthed; larger loads get a single phase 11kV/500V transformer with a centre tap earthed. Some farm equipment (I am told - I have never seen this) is rated for 480V single phase. It is very unusual for a domestic installation to get more than one phase and neutral. But 3-phase can be done - the supply company don't mind putting it in if they think you'll buy a lot of electricity! Philip.

26 years, 7 months

GEM GPL'd?

by healyzh＠aracnet.com

Here is a site that claims Caldera just GPL'd GEM. http://www.devili.iki.fi/cpm/gemworld.html I've no idea of the validity of this statement, but apparently the guy running the site browbeat Caldera into releasing it. They've got a pretty good selection of GEM PC software, and it sounds like other stuff elsewhere on the site. If you're interested in such things. Zane | Zane H. Healy | UNIX Systems Adminstrator | | healyzh(a)aracnet.com (primary) | Linux Enthusiast | | healyzh(a)holonet.net (alternate) | Classic Computer Collector | +----------------------------------+----------------------------+ | Empire of the Petal Throne and Traveller Role Playing, | | and Zane's Computer Museum. | | http://www.dragonfire.net/~healyzh/ |

26 years, 7 months

It's Alive!!!

by healyzh＠aracnet.com

Wow!!! I think I just smoked the power distribution unit on the RL02 rack, but I just booted RT-11 V4 on the PDP-11/44! It is Alive!!! Zane | Zane H. Healy | UNIX Systems Adminstrator | | healyzh(a)aracnet.com (primary) | Linux Enthusiast | | healyzh(a)holonet.net (alternate) | Classic Computer Collector | +----------------------------------+----------------------------+ | Empire of the Petal Throne and Traveller Role Playing, | | and Zane's Computer Museum. | | http://www.dragonfire.net/~healyzh/ |

26 years, 7 months

The TI 34010

by dpeschel＠u.washington.edu

I've been reading back issues of Micro Cornucopia... They have a lot of glowing things to say about the TI 34010. Has anyone used one? They sound very powerful and they fit my ideas about what graphics hardware should do. my ideasx: easy programmability and flexible memory architecture are good. Comprehensive text routines are as important as graphics routines. If hardware is proprietary (like 3D cards for IBM clones) or nonstandard (like cheap VGA cards for IBM clones) or the OS can't deal with it, I don't really want to deal with it either. -- Derek

26 years, 7 months

NEC APC III Boot Disk

by jolminkh＠nsw.bigpond.net.au

There was a thread earlier about APC III's and I recall people asking for boot disks. I found a working machine today with a hard drive, and have made a teledisk image of a 360k boot disk that works if the machine has an SLE card fitted. It's MS Dos 2.11 . Email me for a copy. If there is no SLE card it would need the original OS on a quad density disk. The SLE card in this one wasn't labelled as such, just a card in an expansion slot with an 8086 chip and Eproms on it. Hans

26 years, 7 months

Highgate's PDP-8 Web Page Updated!

by mcquiggi＠sfu.ca

Hi Gang: This evening I completed some long-overdue information updates on the highgate.comm.sfu.ca PDP-8 web page. 27 new pdp-8 related documents are now available. About two dozen more items will be added shortly. See http://highgate.comm.sfu.ca/pdp8 for details. The new items are flagged. Thanks as always to "scanmaster" David Gesswein for the content. Kevin --- Kevin McQuiggin VE7ZD mcquiggi(a)sfu.ca

26 years, 7 months

Good Weekend, bad weekend...

by jimw＠agora.rdrop.com

Seems like someday you just can't buy a break... Good or bad, and sometimes they come in lots! The past two weekends have been both good and bad around the Computer Garage... The good: some major new additions to the collection The bad: my faithful Chevy Surburban that has provided transport for so much gear over the years has suffered a rather major mechanical failure... (sigh) Preferring to think to the good side tho... I've added a fairly complete Tektronix 4054 graphics computer system to the collection. Along with it came a hard copy unit, external tape drive, a rather large flat bed plotter, and a full set of docs and tapes! Now I've just got go get a large enough flat spot cleared out to light this critter up! (it supposedly all works!) And man, that is one LARGE (19 inch) storage tube!) Then just today I picked up a rather complete set of IBM F.E. manuals and docs for the early Unit Record / EAM machines! The docs are in fine shape for their age (received them from a 31 year IBM vet.) and appear to cover all of the early key punches, sorters, collators, tabulating machines, etc... Most cool! And to go with it, I just picked up an IBM model 82 sorter! (that was on Friday tho...) Also sorting thru the acqusitions from the Paxton auction last week... DEC TU-81+ tape drive, MINC-11, and RA-81 hard drive, a pair of HP 1000F (aka 2117F) CPUs (anyone got docs on these critters?), a Tektronix 4006-1 graphics terminal and model 230 digital unit, an HP 9000/20 (aka 9000/520) workstation, and other minor random goodies... I'd be having an even better time if I were not so bummed over the 'Sub... But, all in all, not a totally horrible weekend or two, eh? And hopefully, I'll get caught up with my photography of the collection as I finally broke down and picked up a digital camera, which has already made it's debut with the shots of the Paxton auction. If of course, I can stop running around picking up new equipment and crawling under vehicles having to fix things... B^} (ok... so maybe if I could just stop having to crawl under vehicles!) -jim --- jimw(a)computergarage.org The Computer Garage - http://www.computergarage.org Computer Garage Fax - (503) 646-0174

26 years, 7 months

RARE: Original Macintosh found!!

by gregorym＠cadvision.com

At 04:57 PM 4/25/99 -0700, you wrote: >>Just kidding, but I am looking for some info. I found a good condition 128K >>Mac at a sale today, with most of the original packaging and materials. I'd > >If it says 128k, its not the first Macintosh, which was just labeled >Macintosh. The 128k marking didn't come out until later models were >released to differentiate it. > > My original post may have been misleading. It just says "Macintosh" on the back of the case. I'm assuming that it's a 128K Mac because: it has a 400K floppy drive, no hard drive port on the back, and all of the system software (Finder, MacWrite, MacPaint) is version 1.0, dated early in 1984. Also, all of the accompanying documentation seems to be from the original issue. There's a "limited time" subscription offer to a brand new magazine called MacWorld - think they'll still honour it? How can I check the memory capacity, to see if it's a 128K or a 512K Fat Mac? I'm not that familiar with Macs. Regards, Mark.

26 years, 7 months

PC question

by jolminkh＠nsw.bigpond.net.au

This all sounds like a lot of trouble. They all had labels on the front you know. The AT had "IBM Personal Computer AT", the XT similar with "XT". The only one that looks indistinct was the original PC which just said "IBM Personal Computer". Failing that they had labels on the back. The PC was model 5150, the XT model 5160 and the AT model 5170 as I recall. Hans Olminkhof -----Original Message----- From: Richard Erlacher <edick(a)idcomm.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Monday, 26 April 1999 10:09 Subject: Re: PC question >If they are IBM boxes, then the shape will give that away. If the box has a >sloped front, then it's an XT. If the floppy is a full-height drive, it's >an XT, and if you look inside it will be really obvious, in that the XT >motherboard is confined to the area to the left (as you face the front of >the box) of the power supply. Most obvious of all, of course, is the fact >that the XT had no 16-bit slots in the motherboard. XT-types generally had >a floppy controller and a separate hard disk controller. The AT had a >single controller for both. > >Dick > > > >-----Original Message----- >From: Megan <mbg(a)world.std.com> >To: Discussion re-collecting of classic computers ><classiccmp(a)u.washington.edu> >Date: Sunday, April 25, 1999 5:55 PM >Subject: PC question > > >> >>Yesterday, at the KS10 move, I came away with two IBM PCs, but I >>don't know enough about them to know if they are the AT or XT >>models... they both have a 5.25" floppy and a hard drive, and >>both have color monitors. >> >>They are both desktop boxes... the monitors were sitting on top >>of them. >> >>So, how do I tell... >> >> Megan Gentry >> Former RT-11 Developer >> >>+--------------------------------+-------------------------------------+ >>| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | >>| Unix Support Engineering Group | (home): mbg!world.std.com | >>| Compaq Computer Corporation | addresses need '@' in place of '!' | >>| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | >>| Nashua, NH 03062 | "pdp-11 programmer - some assembler | >>| (603) 884 1055 | required." - mbg | >>+--------------------------------+-------------------------------------+ >

26 years, 7 months

It's Alive!!!

by mbg＠world.std.com

>No, it's really wierd. I smelled smoke, at which point I started >worrying, and then realized the RL02 wasn't spun up, so I figured that >was it. Then I noticed the breaker on the back of the RL02 was tripped, >so I switched it back on, it started to spin up, and it tripped again. >Plugged it into the surge supressor, and it worked. I didn't notice any >load buzzing, but then with the way stuff is arranged at the moment for >testing, I probably wouldn't, unless it was REALLY loud. Just to let you know... when the RLs are powered on, there is about a 10 second or so period in which they sound like they might be buzzing... the motor is turning very slowly during that time. After it does this, you should hear a click as the buzzing stops and the cover interlock disengages. Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+

26 years, 7 months

PC question

by edick＠idcomm.com

If they are IBM boxes, then the shape will give that away. If the box has a sloped front, then it's an XT. If the floppy is a full-height drive, it's an XT, and if you look inside it will be really obvious, in that the XT motherboard is confined to the area to the left (as you face the front of the box) of the power supply. Most obvious of all, of course, is the fact that the XT had no 16-bit slots in the motherboard. XT-types generally had a floppy controller and a separate hard disk controller. The AT had a single controller for both. Dick -----Original Message----- From: Megan <mbg(a)world.std.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Sunday, April 25, 1999 5:55 PM Subject: PC question > >Yesterday, at the KS10 move, I came away with two IBM PCs, but I >don't know enough about them to know if they are the AT or XT >models... they both have a 5.25" floppy and a hard drive, and >both have color monitors. > >They are both desktop boxes... the monitors were sitting on top >of them. > >So, how do I tell... > > Megan Gentry > Former RT-11 Developer > >+--------------------------------+-------------------------------------+ >| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | >| Unix Support Engineering Group | (home): mbg!world.std.com | >| Compaq Computer Corporation | addresses need '@' in place of '!' | >| 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | >| Nashua, NH 03062 | "pdp-11 programmer - some assembler | >| (603) 884 1055 | required." - mbg | >+--------------------------------+-------------------------------------+

26 years, 7 months

RARE: Original Macintosh found!!

by gregorym＠cadvision.com

Just kidding, but I am looking for some info. I found a good condition 128K Mac at a sale today, with most of the original packaging and materials. I'd like to know if anything's missing, other than the original packing box for the system unit itself. I'd like to have a complete set of Mac Ver. 1 materials. What I have is: -the original boxes for the mouse and keyboard, with stylized colour paintings of a mouse and keyboard on the boxes. -a plastic box with the word Macintosh at the upper left, and a stylized Apple at the lower right. It contains a Mac System Disk, a disk Guided Tour to the Mac, an audio cassette Guided Tour, a "Programmers Button" option, several Apple computer stickers, several Apple disk labels, a Macintosh manual, and power cord. -a MacWrite/MacPaint box, with a MacWrite/MacPaint disk, a disk Guided Tour to MacWrite/MacPaint, an audiotape Guided Tour, and a MacWrite manual. Should there be a separate MacPaint manual as well? Any help would be much appreciated. Mark.

26 years, 7 months

The "FIRST PC"...

by yakowenk＠cs.unc.edu

This not only makes it the first home computer, but the first kitchen computer as well! Didn't Honeywell try to market a kitchen computer in the late 70's or early 80's? I'm sure it would have taken off, if only they had been the first. :-) But, sadly, without internal video circuitry, it can't be a personal computer. <snort!> :-) Bill. On Sat, 24 Apr 1999, Max Eskin <max82(a)surfree.com> wrote: ] ... ] Speaking of which, wasn't the Zuse built on a kitchen table in the ] mid-30's? Wouldn't that make _it_ the first personal computer?

26 years, 7 months

Wanted: PC-4 thermal printer

by yakowenk＠cs.unc.edu

I got this note, seems this guy saw the Rescue Squad web page, but isn't generally interested in classic computers; he just wants one specific part. If you can help him out, kindly reply directly to him. Gracias, Bill. ] Name Steve King ] E-mail address sfjk1(a)usaf.net (delete 2 f's) ] State Florida ] Computers of interest Radio Shack TRS-80 Model PC-4 "Pocket Computer" ] Note I am looking for the thermal printer, ] in working order.

26 years, 7 months

Pictures of my damaged core

by ethan_dicks＠yahoo.com

Not to follow up my post with another post, but I found a typo (and I suspect some of you did, too) --- Ethan Dicks <ethan_dicks(a)yahoo.com> wrote: > Here's some photos of that stack I got back in '82 with a partial PDP-8/L http://www.infinet.com/~erd/retrocomputing/pdp8/pix/coreassy.jpg - external view http://www.infinet.com/~erd/retrocomputing/pdp8/pix/coremat1.jpg - one bad mat http://www.infinet.com/~erd/retrocomputing/pdp8/pix/coremat2.jpg - another one Sorry for the inconvenience. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

26 years, 7 months

It's Alive!!!

by mbg＠world.std.com

>Oh, and don't worry, the VT420 is only for testing purposes, I've got >VT100's and a DECwriter II for the PDP-11/44 :^) Although the DECwriter >II will take some serious work before it's usable. I know what you mean... although the KS10s we got the other day had video terminals for the console, we also got a true LA36 in order to have that is a more traditional console for such an old beast... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+

26 years, 7 months

The "FIRST PC" and personal timelines (Was: And what were the80s id AA20656; Fri, 23 Apr 1999 18:48:08 -0400

by allisonp＠world.std.com

<I think what they don't realise is that computers at this point had <names, not numbers. 20 is probably quite close. I know there's a site <that catalogues them. I think at this point, the firts generation IBM 600' <hadn't been been built yet, although they have been in planning. I'd have to hunt on that too. I believe that the 1952(ish) was the year of the first production computer (univac, vacuum tubes). It was '58ish maybe later for the first production transistor machines. I'd extend that with some error the 60s would be the advent of the first volume production machines. (IE: hundreds of a kind). The watershed event was the forcasting of an election with a computer on TV. That would bring the idea of a computer from the labratory to something people could relate to. Radios went through the same curve though the peried of time was longer. Allison

26 years, 7 months

The "FIRST PC" and personal timelines (Was: And what were the80s

by edick＠idcomm.com

Well, Sellam, it's a question of statistics. The population was about 225 Million back then +/- some number, and the people in the US or even the world who had any notion of what a digital computer was was probably around a hundred, well, maybe a thousand. Now, you started out with an "average" American. Of the thousand or so to whom owning a computer didn't amount to slavery, how many do you think could afford to spend the equivalent of a half-year's groceries, during the period when the word "recession" was invented, on something the maximal function of which was strictly limited in purpose to some form of mental masturbation? They couldn't use the excuse that "we could use it to manage our checking account . . ." or some such, because it wouldn't do that. Do you think the average American could afford to spend that kind of dough on something he didn't need? Do you think he'd have spent the dough on something it probably would have benefitted him NOT to have? . . . like a digital computer toy? Dick -----Original Message----- From: Sellam Ismail <dastar(a)ncal.verio.com> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Saturday, April 24, 1999 2:27 AM Subject: Re: The "FIRST PC" and personal timelines (Was: And what were the80s >On Fri, 23 Apr 1999, Richard Erlacher wrote: > >> No, Sam, those were not necessarily MY attitudes. I, after all, was only 6 >> years old during most of 1952. However, I'd submit that my statement is >> more or less correct, inasmuch as most Americans had no idea what a digital >> computer was in 1952. My grandfather worked for one of New York's large > >What does having "no idea what a digital computer was in 1952" have to do >with being able to afford one? Can you make an argument and stick to it >please? > ><...> >> whatever was the model of the day, and they got the work done. That's what >> the average American thought of when you asked him about a computer, though >> most didn't really even recognize the word. > >Ok, thanks for that history but it does nothing to further your argument, >nor does it have any relevance to your assertion. > >> In 1954-55 a friend of my parents bought an airplane for $300. He also >> liked those British sports cars, which traded, 2nd-hand for about $300 in >> the late '50's, though they were not that "reasonable" by the time I wanted >> one (goodness only knows why I wanted it). > >Oh?? I thought $300 was hardly an amount one could afford to be spending >in the 50s! Seems like it wasn't that big of a deal after all. > >> Back to the attitudes . . . I certainly hope that you don't purport YOUR >> attitudes to be typical. I know mine aren't. What brings balance to a >> discussion is the presentation of perceptions. > >No, I'm not so arrogant (or myopic). > >> One other point . . . I don't know how you can claim to know about what's on >> the mind of an "average" American. People who, ten years ago, were rabidly > >I made no such claim. However, you pretty much DID make such a claim. > >Sellam Alternate e-mail: dastar(a)siconic.com >--------------------------------------------------------------------------- --- >Don't rub the lamp if you don't want the genie to come out. > > Coming this October 2-3: Vintage Computer Festival 3.0! > See http://www.vintage.org/vcf for details! > [Last web site update: 04/03/99] >

26 years, 7 months

It's Alive!!!

by CLASSICCMP＠trailing-edge.COM

>Wow!!! I think I just smoked the power distribution unit on the RL02 >rack, but I just booted RT-11 V4 on the PDP-11/44! It is Alive!!! Good! Why do you say you smoked the power distribution box? Is it buzzing loudly, by any chance? This is usually a sign of a bad capacitor in the relay/contactor power supply, and is easily repaired. -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927

26 years, 7 months

It's Alive!!!

by mbg＠world.std.com

>Wow!!! I think I just smoked the power distribution unit on the RL02 >rack, but I just booted RT-11 V4 on the PDP-11/44! It is Alive!!! Congrats on booting! Sorry the PS smoked... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com | | Unix Support Engineering Group | (home): mbg!world.std.com | | Compaq Computer Corporation | addresses need '@' in place of '!' | | 110 Spitbrook Rd. ZK03-2/T43 | URL: http://world.std.com/~mbg/ | | Nashua, NH 03062 | "pdp-11 programmer - some assembler | | (603) 884 1055 | required." - mbg | +--------------------------------+-------------------------------------+

26 years, 7 months

The "FIRST PC" and personal timelines (Was: And what were the80s id AA20656; Fri, 23 Apr 1999 18:48:08 -0400

by allisonp＠world.std.com

<(if available at 1/4th of a year salery) and I can't see any <difference to the situation in the 70s - the same group of electonic <fascinated people would have taken the chance. < <The effect is just that there was no such device. And ther ewas more importantly no concept of having/building one outside of university circles (how did they do it!). Allison

26 years, 7 months

Building Core, Stage 2

by allisonp＠world.std.com

<1) I'm using copper clad board to provide a ground plane "under" the core. <After my last message it became obvious that this was the other half of th <winding "through" the core. Not required. Any whire with durrent passing through it has a field around it. That is all that is required. More turns only reduce the current required to attain a given field. <2) I'm using "magnet" wire (enameled copper wire) for the core wire. I'm <guessing it can take a couple of amps for a short period of time. I'm not <sure that is sufficent to "switch" the #2 nut I'm using but we'll see. The current can be quite high as those pulses will be short (microseconds). <3) Allison referenced a waveform that looked like this: Keep in mind that will switch the core in both directions. that was mostly a test signal for trying materials. <4) The diagram in the 8a manual shows the sense wires going through one se <of cores, looping and coming back through another set. The sense wire is <also used as the 'inhibit' wire when one wants to write a zero. This is <done by reversing the X or Y current so that the selected cores don't get <full write current (and thus don't switch.) Yep the two matic selects and the sense/inhibit wire. Some planes used four wires with the inhibit being seperate. <5) So this is the plan: < put three wires through the nut and wire them up as follows: < -- < 1/h select ----------\ | | /----- GND < 1/h select ---------------| |-------------- GND < sense + ----------/ | | \----- sense - For testing a "core" only two are needed. makes life simpler. < The scope will display the current on the select lines on channel 1 < the sense lines on channel 2 (floating ground) Good! <6) When the current is sufficient, I should see a pulse on the sense line. < (This is the hypothesis part, now to apply the scientific method) Actually even if the current is low there will be a pulse coincident with the drive pulse (transformer action). However when the core switches the waveform will not corospond to a 1:1 transformer and also it will be shifted in time. If the core is not suitable the signal may not be visible. Allison

26 years, 7 months

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