- test-drb@ccmp.vtda.org - classiccmp.org

by KFergason＠aol.com

In a message dated 4/21/99 3:29:10 PM Central Daylight Time, dastar(a)ncal.verio.com writes: >> of any operating system or application software for it. I don't believe I >> ever saw a real SC/MP based computer. > > Richard, the rest of the world does not peer through the same blinders you > have on. > > Sellam Alternate e-mail: dastar(a)siconic.com > Name a non-homebrew SC/MP based computer. (note, I believe one existed, but memory is fuzzy till i get home to the old magazines) Kelly

27 years, 3 months

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And what were the 80s like for you? (Was: z80 timing...

by KFergason＠aol.com

In a message dated 4/21/99 4:33:49 PM Central Daylight Time, jim(a)calico.litterbox.com writes: > Heh. No. I got my first PC in 1990. 386s had just come out, but an XT was 386's came out in 1986. Kelly

27 years, 3 months

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z80 timing... 6502 timing

by KFergason＠aol.com

In a message dated 4/21/99 4:20:10 PM Central Daylight Time, dastar(a)ncal.verio.com writes: > Is this a challenge of some sort? The comment I made was referring to > Richard's overall outlook on computer development throughout the past two > and a half decades. But as far as SC/MP based computers go, the next time > I visit my warehouse I'll take take note of the singleboard SC/MP > computers I have. > > In the meantime, Hans will tell you about the ones he has in his > collection. > call it what you will. I simply asked for a name. Kelly

27 years, 3 months

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And what were the 80s like for you? (Was: z80 timing...

by CLASSICCMP＠trailing-edge.COM

>> *My* gauge of when the PC became the dominant force was when: >> 1. Dr. Dobb's started carrying few articles other than ones talking about >> MS-DOS >> and >> 2. The quantity of IBM PC ads in the back of BYTE outinched the >> number of S-100 ads >> Looking at my back issues, I'd draw the line at 1985. >Did Dr. Dobb's and Byte really represent the mainstream? Dr. Dobb's in the early 80's kind-of split itself between dedicated hobbyists and professional (business-based, usually) microcomputer programmers, with a lot of influence from the mini world. BYTE was really wide-ranging, and actually did a pretty good job at covering not only what the current hot seller was, but also exploring into the nooks and crannies of the industry as new things came out. *Both* lost most of their variety when the IBM PC and early clones steamrolled through. >How about something even more subjective: >IBM PC became the dominant force when, ... >The fun went out of the industry. That's kind-of-sort-of the same thing :-(. >Who can assign dates to when the industry lost its sense of humor? Such >as: when Kentucky Fried Computer became NorthStar? > when Thinker Toys became Morrow Designs? > when Intergalactic Digital Research became Digital Research Inc.? The DRI change was before 1976 by a year or two, I believe. My first copy of CP/M (1.3) says "Digital Research" under Gary Kildall's signature on the license, and that's from 1976. Wasn't there also "Itty Bitty Machines" which was forced to change its name when leaned on by a slightly larger company with similar initials? -- 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

27 years, 3 months

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And what were the 80s like for you? (Was: z80 timing...

by CLASSICCMP＠trailing-edge.COM

>> The majority of home computers, though, used one of >> these two, at that time. Several years later, we found the 6510 and 6809 in >> commercially interesting applications, but not for as long a period as the >> Z-80 and 6502. These two had a life of nearly ten years before the IBM-PC >> and its clones wrenched the home computer market from their grasp. >10 years? >Does this imply that the PC was not the dominant force until the end of >the 80s? >[this is a comment about market, NOT an endorsement] *My* gauge of when the PC became the dominant force was when: 1. Dr. Dobb's started carrying few articles other than ones talking about MS-DOS and 2. The quantity of PC-Clone ads in the back of BYTE outinched the number of S-100 ads Looking at my back issues, I'd draw the line at 1985. -- 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

27 years, 3 months

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Need Info on DEC Board: USDC-1101

by CLASSICCMP＠trailing-edge.COM

>They are made by (apparently) USDC, model number 1101, revisions "01" and >"BG". The chips are marked circa 1982. They have a Z80, som EPROM, a >couple of PALs, and a 40 pin IDC header. They are half-height boards ( >i.e. two sets of fingers). "LSI-11 Host Interface" is silk screened onto >the board under the part number. > >Can anyone tell me what these are? They came out of an 11/23 box badged >11-DM4, althought the box is in the truck and I may have the DM$ slightly >incorrect. USDC= U.S. Design Corporation. They're based in Maryland, not too far >from where I now live. They sold (among other things) disk subsystems. The one you have emulates RK06/RK07 drives, and hooked (via the 40 pin connector) to an external box that had a hard drive (either a 5.25" MFM or a 8" non-MFM) with electronics that converted the native drive interface to the 40-pin interface. You might have seen the appropriate drive boxes in my storage space in Surrey, if you remember our trip there :-). They're 5.25" rack-width boxes, have black fronts with a row of bar LED's that blink in a cylon patterm when running, and are about 25" deep - you ought to head back out to UBC and see if there are any USDC boxes meeting this description there. I still have the drives and the interfaces, but it's been years since I've powered them up. The controller is 22-bit-Qbus capable, but the PDP-11 OS's only know of Unibus RK06's/07's, so machines with more than 256kbytes of memory generally had USDC patches made to the OS drivers so they knew how to do DMA to high memory. -- 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

27 years, 3 months

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The Paxton auction: any interest in rescues

by Innfogra＠aol.com

It was a very cheap sale. Unfortunately it means that the scrappers got most of it. Checkout is still going on so there is a chance for some rescues if anyone is interested. I am posting the following list in hope that someone is interested in the misc. I will negotiate with the scrappers who bought the following if you are interested. Cheap offers are OK but we must move fast. Vector 3 (not a Soroc) with attached hard/floppy drive. The power cord for the HD/FL is broke. The CPU powers up nicely and all has worked in the past. The glare guard fabric is torn. Two Vector 4s with hard and floppy drives. They work but I can't find keyboards. Vector DD-5026 dual floppy accessory. Andromedia Systems Dual 5 1/4 floppy disk drive, DDMDS-B, SN 21. Could this be for DEC equip. MD 10 (Media Distributing Mfg.) Model RM11, SN 0061. One of the first small systems hard drive. Untested. CCS (California Computer Systems) 12 slot S 100 Mainframe with 64K static ram (4 - 16K boards), 2850 system processor Z80A, 2805 terminator, 2422 Floppy controller, 2830, 6 SIO. Missing the faceplate and has scratches on finish. Goes with a complete Dual 8" external drive. Set up as a USPS controller. IBC Multi-User Business computer, running a Z80H. DBS 16 4 user MPM system, has a 10 meg HD and has a serial number of 48. No terminals. Appears to work. Vista, V-1100 dual 8" disk drive case with dual Shugart 860-1 drives. Another drive case is a JMR Electronics with two Tandon TM848-01s. Powers up. Commodore dual disk drive. 4040 I think. HPIB interface. Compupros, Two 16 slots wi Tarbel Z80 CPU/IO, Ram 16 and the Tarbel MD 2022 8" Floppy controller. Integrand 7 slot S 100 Mainframe with the funny wide slot 5 1/4" disk drive. No cards. A Columbia 1202-4/110 Drive cabinet with an 8" HD and an 8" Floppy. A 10 slot Compupro with a single 8" SS drive, 8085/88 CPU, Ram 16 180A and a Disk One. A US Data dual 8" SD disk drive cabinet. A Telebyte TBX front loading reel Tape drive with serial IF. A Televideo TS803 that boots MS Dos. Works fine. a Symmetric 375 for parts, no HD (1/2 of the power of a VAX 750)! I have also made a deal with another scrapper to offer both 8 " hard and floppy drives. Several Quantum 2020s, 2040s and 2080 HDs. Three IMI 7720 HDs Shugart 801 and 851 full Ht Floppies Mitsubishi 2894 - 63B Full Ht. Floppies DSDD also Mitsubishi 1/2 Ht 2896-63B DSDD Floppies, Tandon 848 1/2 Ht floppies of different versions, NEC 1165-FQ & 1 1165-A 1/2 Ht floppys, and Shugart 810 and 860 1/2 Ht floppies, all 8" drives. All are working pulls, heads parked but untested. Looking to get $10 to $40 depending on size, condition and quantity. Shipping additional. I also believe the VAX 730, the RA60 and the RA81s are headed for scrap. Any Interest out there? Paxton

27 years, 3 months

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z80 timing... 6502 timing

by edick＠idcomm.com

For the longest time, the TMS 9900 didn't appear in anything one could consider a reasonable computer. There was one model I saw at a colleagues home which had expansion capability, but he often complained that cards for interesting applications, like mass storage, etc, were not available. I didn't pursue it and so I believe(d) it to be true. I saw one ad for an SC/MP, in '77, but that one was a homebrewed model. Other than that, it was not of much interest here. Was that not the case in Germany? The processor was still in National's data book, but I really wasn't then and am not now of any operating system or application software for it. I don't believe I ever saw a real SC/MP based computer. Dick -----Original Message----- From: Hans Franke <Hans.Franke(a)mch20.sbs.de> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, April 21, 1999 2:10 PM Subject: Re: z80 timing... 6502 timing >> I suppose that's true, Hans, BUT, in1982, there were few other processors >> than the 6502 and Z-80 in popular use, with the exception of the 8080A and >> the 8085, of course. The majority of home computers, though, used one of >> these two, at that time. Several years later, we found the 6510 and 6809 in >> commercially interesting applications, but not for as long a period as the >> Z-80 and 6502. These two had a life of nearly ten years before the IBM-PC >> and its clones wrenched the home computer market from their grasp. > >in 1982, the 9900 was also big and beasts like SC/MP where still on >the run (and 680xx, 808x and 160xx comming up), but you're right if >you want to pich the two mayor player in the SOHO market. > >But still, a general measurement includes them. > >Gruss >H. > >-- >Stimm gegen SPAM: http://www.politik-digital.de/spam/de/ >Vote against SPAM: http://www.politik-digital.de/spam/en/ >Votez contre le SPAM: http://www.politik-digital.de/spam/fr/ >Ich denke, also bin ich, also gut >HRK

27 years, 3 months

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Need Info on DEC Board: USDC-1101

by mcquiggi＠sfu.ca

Hi Gang: I just returned from the local university junk sale, and acquired (among other detritus) two Q bus boards. They are made by (apparently) USDC, model number 1101, revisions "01" and "BG". The chips are marked circa 1982. They have a Z80, som EPROM, a couple of PALs, and a 40 pin IDC header. They are half-height boards ( i.e. two sets of fingers). "LSI-11 Host Interface" is silk screened onto the board under the part number. Can anyone tell me what these are? They came out of an 11/23 box badged 11-DM4, althought the box is in the truck and I may have the DM$ slightly incorrect. Thanks, Kevin -- Kevin McQuiggin VE7ZD mcquiggi(a)sfu.ca

27 years, 3 months

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Sun 1 question

by CLASSICCMP＠trailing-edge.COM

>There's a rough equivalent to the "DEC Field Guide" for Sun systems. >It's the "Sun Hardware Reference", and is by James W Birsall, and >(at least it used to) is posted to comp.sys.sun.hardware semi-regularly. > >One version on the web is at > > http://stumbo.vm.com/~techrat/faq_hardware/hwref0.html I should also point out that there's a good amount of information in that FAQ that non-Sun collectors would also be interested in. Settings for many Multibus and VME modules, settings for many of the Emulex MFM and ESDI<->SCSI bridge controllers, settings for at least some of the more common QIC drives, some very basic information on older SCSI and IPI drives, and a pointer to the "Sun format.dat" table, which has geometry tables for common configurations of many SMD drives. There are also some gaping holes in the information that I'm sure we could help fill in, too :-). -- 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

27 years, 3 months

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PDP-11/44 CPU Configuration

by CLASSICCMP＠trailing-edge.COM

>This is the configuration that the machine came in, except it was missing >the RAM and DELUA, I've added both where they had originally been according >to the diagram on the CPU cover, except I'm not sure if there were 1 or 4 >RAM cards originally. > >Pardon such basic questions, but this is the first time I've worked on a >UNIBUS system, I'm used to working on my Q-Bus systems. Speaking from decades of experience, you *do not* put a Unibus machine together in a big configuration, especially from mix-and-match used parts, and get it to work. You go down to the most basic configuration possible, and then add parts one at a time, testing as you go. I'd recommend that anyone in a situation similar to yours strip the machine down to a single system unit (i.e. pull the M9202 linking the backplane segments together and put a terminator in slot 14), with a single memory board and a single disk-like peripheral, then work their way up. Of course, you need a terminator before you can do any of this, and preferably a few spare grant continuity cards (but we'll make sure these shortcomings are fixed shortly!) -- 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

27 years, 3 months

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Repairing core

by yakowenk＠cs.unc.edu

On 19 Apr 1999, none other than Sellam Ismail <dastar(a)ncal.verio.com> himself wrote: ] I don't see what the big attraction to a core plane is. You stick it on ] your wall. Whoopee! Look at me, I have a core plane on my wall. Big ] fricken deal. Nobody even knows what it is anyway. From afar it looks ] like a black square. Closer up it looks like a piece of a window screen. ] ] Unfortunately, my rant is not going to stop the lame-o's selling it from ] hyping it up as some cool collectable, and it's not going to stop the ] techno-wannabees from buying it to stick on their wall. So what kind of wall hanging is more appropriate for a geek? Besides, where the heck am I going to find the rest of a Univac to plug it into? I like the "bait" theory and all, but... And too, I'd wager that most of your collection is of the "look at that" variety. You can't tell me you actually _use_ more than a handful of them. I've seen your schedule, remember? And let's not drag bubble memory into it, eh? Nyah, nyah, and nyah. Bill.

27 years, 3 months

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Ancient disk controllers

by yakowenk＠cs.unc.edu

On 19 Apr 1999, that Cool Frood ard(a)p850ug1.demon.co.uk (Tony Duell) wrote: ] Yes. I have the Signetics data sheets for the 8x300, 8T31, etc. They're ] in an old Mullard/Philips data book which also covers the 68000. I recently scored a Signetics data book with 8x305 data in it, along with a Fairchild databook (F8) and an RCA databook (1802). It's weird, I'm almost as happy about it as if I had gotten machines based on those processors! Cool Beans! Bill.

27 years, 3 months

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PDP-11/44 CPU Configuration

by healyzh＠aracnet.com

I've finally got power for my PDP-11/44 so I'm getting ready to start testing it out, and as a result have made a careful diagram of the CPU prior to pulling the cards so I can test the Power Supply. It took some doing, but I found Tony's message from June 10th of last year telling me how to test it :^) In doing up the diagram I've discovered a few problems. I'd appreciate it if someone that knows what they're looking at could take a look a the diagram though. The diagram is here: http://zane.brouhaha.com/healyzh/images/pdp1144cards.GIF I realize I'm missing M9302 UNIBUS Terminator. Slot 15 is actually the gap between the two backplanes in the cabinet, and Slots 25-29 don't exist. I suspect I need "Grant Continuity Cards" in Slots 10-12 since I don't have memory in them. Is there anything else that I'm missing, or does anyone see any problems with this configuration? This is the configuration that the machine came in, except it was missing the RAM and DELUA, I've added both where they had originally been according to the diagram on the CPU cover, except I'm not sure if there were 1 or 4 RAM cards originally. Pardon such basic questions, but this is the first time I've worked on a UNIBUS system, I'm used to working on my Q-Bus systems. I did get one pleasant surprise, I'd thought I was missing the FP11. 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/ |

27 years, 3 months

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The Paxton auction: any interest in rescues

by rigdonj＠intellistar.net

I'd go with a pickup load of $$$ and come back with several loads of junk, er, umm, stuff. Good thing I'm on the wrong side of the country. Joe At 11:05 AM 4/21/99 -0700, you wrote: >If I went down with a pickupload of that stuff I might bring back a pickup >load of other stuff.... > >George > >========================================================= >George L. Rachor Jr. george(a)racsys.rt.rain.com >Beaverton, Oregon http://racsys.rt.rain.com >United States of America Amateur Radio : KD7DCX > >On Wed, 21 Apr 1999, Sellam Ismail wrote: > >> On Wed, 21 Apr 1999, Marvin wrote: >> >> > Hmmm, another thought ... VCF 3.0 is coming up and would be a great place to >> > sell off these systems if you have the time, room, and inclination to do so! >> >> Yeah, good point. I'll wager that if you were to put this all in the back >> of a pickup and drive down to VCF 3.0 for the weekend, you'd drive back up >> with a stack of bills in your pocket and an empty pickup. >> >> 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] >> >> > >

27 years, 3 months

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

by CLASSICCMP＠trailing-edge.COM

>I'm serious. I really have wanted to build something like this. In terms >of size, the problem isn't the wiring, it's the redundant circuitry. Most of the DEC core planes use a fair number of special-purpose transistor arrays (often specially matched) for drivers as well as pulse transformers and delay lines. If you look back at alt.sys.pdp8 archives (or its mailing-list twin, PDP8-LOVERS) you'll find some suggestions for part substitutions and/or rebuild directions. I believe that at least one of the electronics rags in the Lasnerian mid-70's (Radio Electronics? Popular Electronics?) published an article on using surplus core arrays that were readily available at the time, but the article was remarkably detail-free when it came to the actual details of driving and sensing. There were at least a few implementations of S-100 core memory in the mid-70's, and one of them was a S-100 to Unibus translator of sorts. (Not to be confused with the IMSAI S-100/Unibus shared memory module, which is in several of my IMSAI price lists from 1977/1978 but which I believe to be vaporware.) -- 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

27 years, 3 months

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heads up; OSI Challenger 1P

by allisonp＠world.std.com

<Well, I don't know the Electrical Codes across the Pond exactly (I have a <fair idea of the UK regulations...), but I think I read somewhere that <you can't have a 220V outlet for equipment less than a certain wattage <(1.4kW comes to mind). Seems a very silly regulation, but then a lot of <regulations are. Meaningless. I have a pigtail at the box with a 3terminal twist and lock (hubble) wired for 220. It's there as general use for heating in the garage or welding equipment if I had it. I've used it for testing motors (1/4HP) that were clearly under 1.4kw. The codes are aimed at providing reasonable power. Here a 15A/115v is the nominal and 115V/20A is a max but 220/208 at any current the mains can be wired for is common. It would be foolish to sell 220V/1500W hair dryers here as the nominal mains are expected to handle that kind of load. Allison

27 years, 3 months

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UNIBUS Terminators

by healyzh＠aracnet.com

27 years, 3 months

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DEC BC11A-15 Cable

by healyzh＠aracnet.com

27 years, 3 months

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z80 timing... 6502 timing

by edick＠idcomm.com

While your comments are valid observations, I submit, however, that we're coming at this from two different viewpoints. I wish to address the question "Which processor is faster, 6502 or Z-80?" while you want a general comparison of processors. Unfortunately, answering one question doesn't address the other. Dick -----Original Message----- From: Bill Yakowenko <yakowenk(a)cs.unc.edu> To: Discussion re-collecting of classic computers <classiccmp(a)u.washington.edu> Date: Wednesday, April 21, 1999 12:26 AM Subject: Re: z80 timing... 6502 timing >On 19 Apr 1999, Richard Erlacher <edick(a)idcomm.com> wrote: >] It's true that may be more interesting when you have different vehicles, but >] if you're trying to determine which of two is faster, don't you focus on >] those two? Having lots of variations in the hardware only tends to muddy >] the water. > >Obviously, some of us care about vehicles other than those two. >Doesn't muddy _my_ waters one bit. :-P > >I, for one, am interested in processor capabilities independent >of video/disk/etc gorp. Roman numerals isn't going to be a >thorough comparison, but it's better than nothing, and small >enough to be fun. If this is still going on in a month or two, >maybe I'll write an entry myself. As it is now, my schedule >barely allows me to keep up with all the stuff you guys are >writing! > > > >And then, later the same day, regarding my suggestion about >noting the relative ages of processors when comparing their >results, he wrote: >] It's pretty hard to imagine how a limitation like your suggestion would >] apply. Newer processors addressed weaknesses in the older ones. One of >] those was ease of programming. In some cases, e.g. the 6809, the processor >] was designed with a regular instruction set and lots of addressing modes so >] as to make generating code easy. It didn't necessarily make it faster. I >] don't know how elegant such code will ultimately turn out to be. > >If you want to get a handle on which processors were really >better than others performance-wise, you look at the best they >can do on some specific problems. Granted, the results may >not be easy to interpret because of varying environmental >characteristics. Welcome to Earth. Nothing is simple here. > >Obviously, if the 6809 loses to some older processor, its >adherents can still claim ease-of-coding as a benefit. But it >would still be interesting to know if it could regularly get >whomped by a measly, pathetic, sad-excuse-for-a-processor like >the 6502. :-) :-) :-) :-) > >My suggestion was not meant as any sort of limitation, just my >take on what kind of result would be interesting; one way of >interpreting the results. If an older processor doesn't do as >well as the newer one, well, we expected that. But if an older >one outperforms a newer one, there is something worth exploring >there, a lesson to be learned about an improvement really wasn't. > > Bill. > >

27 years, 3 months

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DEC Options Module List

by CLASSICCMP＠trailing-edge.COM

>> In the case of DEC parts, having a dumpster-dived copy of the "Option/Module >> Hardware List" stamped "DEC Confidential" all over it helps a little >> bit :-). >The holy grail of DEC dumpster divers everywhere. >Unfortunately, mine stayed at DEC when I left. I was a good boy when >I left.

27 years, 3 months

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Program Challenge (was Re: z80 timing... 6502 timing)

by ethan_dicks＠yahoo.com

--- Sean 'Captain Napalm' Conner <spc(a)armigeron.com> wrote: > > Problem: Convert a binary value to Roman, using ASCII characters (or > > the native character set if applicable) into a string > > with a termination character (if ASCII, use the NUL (0) > > character). > > > Sorry, I goofed. The longer string is 16 characters long: > > 'MMMDCCCLXXXVIII' plus termination character. In terms of how to represent numbers like 1999 (MIM or MCMXCIX), the rule I learned as a kid was that it was not proper to subtract any numeral >from any other numeral willy-nilly. Only certain combinations were allowed and you had to just memorize them. Here's some links to some pages with something to say about Roman Numerals http://www.cod.edu/people/faculty/lawrence/romans00.htm http://www.col-ed.org/cur/math/math41.txt http://www.mcn.net/~jimloy/roman0.html http://raven.bu.edu/~grozdits/student/roman_num.html ... and we now return you to your regularly scheduled Off Topic discussions... -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

27 years, 3 months

1
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Program Challenge (was Re: z80 timing... 6502 timing)

by mbg＠world.std.com

>And again, more questions: >If I'm right at Megans description, she just include the next lower >digit when it comes to these subtraction rules, and your Algo seams >to be weak at the same point. Let me give an example: >49 would be normaly coded as IL (always remember, it was kind of a >system to reduce writing as much as possible - there are even examples >where the number 248 is written CIIL) while Megan seams to code it as >XXXXIX - basicly wrong - or did I miss something ? I'm not realy >what one can call a DEC-Geek. My code would produce XLIX, not XXXXIX... I guess I'm unclear as to whether any numeral can be used to reduce the value of a higher, subsequent numeral. Using your explanation, 1999 would be MIM, instead of the more standard (as I have seen it) MCMXCIX. Also, what's to stop someone from writing it in a form employing the vinculum: __ III >So do we only have to supporte the one-less rule, or the rule >of one subtraction numeral - or the full possibility with the >goal to reduce writing to a max ? So long as someone can clearly explain the rules to what can be subtracted from what, I'll implement it... (kind of like requiring a spec). Without it, I can only go on what I can find documented in the encyclopedia... 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 | +--------------------------------+-------------------------------------+

27 years, 3 months

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Saving *BIG* Old Iron...

by gentry＠zk3.dec.com

It looks like everything is coming together... We have a team assembled (compiled?) to decommission and move a set of KS10 decsystem-10 36-bit machines and the move happens this weekend! I was in attendance earlier today as the machines were shut down for the final time where they have been for quite a few years. I got a picture of the final systat screen, and they stopped timesharing... We then got busy unloading and shutting down all the disk drives. I then shut down the individual boxes and power controllers for the system cabinets and isolated the cabling (they had LOTS of terminal cables). I then raised all the stabilizing feet and used a tie-wrap to attach the panel keys inside the cabinet. I then closed and latched the front doors. I also did the same for the tape drive cabinets. They're all rolling free and ready to go. On friday, we'll be pre-staging all the disk drives, and on saturday we load-out to trucks. I'll be taking more pictures as we go along... Megan Gentry Former RT-11 Developer +--------------------------------+-------------------------------------+ | Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry(a)zk3.dec.com | | Unix Support Engineering Group | (home): mbg(a)world.std.com | | Compaq Computer Corporation | | | 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 | +--------------------------------+-------------------------------------+

27 years, 3 months

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Counting keystrokes

by Watzman＠ibm.net

Believe it or not, the most common use of keeping keystrokes was for employee evaluation. I remember weekly postings of graphs of "keystrokes/hour" in data entry and word processing departments, with a weekly "prize" [nominal value] for the "best" data entry operator of the week. This and similar productivity measurement measures were not uncommon.

27 years, 3 months

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IBM AT technical reference

by rigdonj＠intellistar.net

Who was I supposed to copy the IBM AT Tech Ref manual? I lost your message. I've made the copy, let me know who you are. Joe

27 years, 3 months

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

by ethan_dicks＠yahoo.com

--- John Dykstra <jdykstra(a)nortelnetworks.com> wrote: > I have several jars of ferrite cores made by IBM sometime in the late > 1950's. I don't know exactly what size they are, but they can be > hand-wired without a stereo microscope. Cool. > As I recall, I used something like #60 enameled wire. One of the > challenges was stripping the insulation off the ends of the wires without > damaging the copper. Heat? Chemicals? Friction? > If anyone is seriously intending to build a demo core memory system, I'd be > glad to provide a couple of hundred cores. I'd recommend something like a > 16x16 array, unless you're looking for a project to make a 20-to-life > sentence go faster. I'm serious. I really have wanted to build something like this. In terms of size, the problem isn't the wiring, it's the redundant circuitry. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

27 years, 3 months

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1802 data sheets: was old data books

by CLASSICCMP＠trailing-edge.COM

>> Good - if you can find some RCA file numbers for the 1801's in there >> for Eric, this'll be a huge step forward in getting the 1801 data sheets >> from RCA and/or Harris. >I know I have nothing on the 1801. It was phased out completely by RCA >in '77 or so. You looked through your 1802 stuff and didn't find a single reference to any 1801 literature? Often just having the reference lets you go to the local EE department and find the appropriate volume in their library (Many departments do have books going back to the early 70's) or in the personal library of one of the faculty members. Unfortunately, little of this stuff is in an online database anywhere, so you really have to do the legwork to track it down. I spent most of my academic career doing such legwork - it's been decades since many of the best tables of thermal neutron cross sections have been published, and I found many of them in dusty corners of little- used labs. Incidentally, I found my HP9100B while searching dusty corners for neutron cross section tables :-). -- 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

27 years, 3 months

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1802 data sheets: was old data books

by CLASSICCMP＠trailing-edge.COM

>> If you want to continue the search further, Harris has online data >> sheets for much of the CDP18XX series (including the classic 1802 >> interface and memory parts), and maybe one of these will have a file >> number for an 1801 data sheet. After you get a file number, you can >> usually have the folks at Harris fax the data sheet to you. >I have full 1802 docs from back when the elf article was published. Good - if you can find some RCA file numbers for the 1801's in there for Eric, this'll be a huge step forward in getting the 1801 data sheets >from RCA and/or Harris. >The 1801 series was a less dense (hence teo chips) version of the 1802 >and was discontinued with the advent of the 1802 back around '76. Yep - this is why you need the file number before you can get any further. The data probably exist in paper form, but aren't indexed in any of the on-line databases that the manufacturers still have. It's like getting obsolete parts from DEC; first you have to convince yourself that such a part still exists, then you have to find the part number, and then you often find it's an off-the-shelf item even though it might not have been produced for 20 years. (Examples of stuff I've ordered in the past few years are RX02 and RL02 drive belts, and even a can of Magna-See.) In the case of DEC parts, having a dumpster-dived copy of the "Option/Module Hardware List" stamped "DEC Confidential" all over it helps a little bit :-). -- 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

27 years, 3 months

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Sun 1 question

by CLASSICCMP＠trailing-edge.COM

>How can I identify Sun 1 cards? There's a rough equivalent to the "DEC Field Guide" for Sun systems. It's the "Sun Hardware Reference", and is by James W Birsall, and (at least it used to) is posted to somp.sys.sun.hardware semi-regularly. One version on the web is at http://stumbo.vm.com/~techrat/faq_hardware/hwref0.html Part 1 is a brief introduction to the various Sun models and backplanes, and Part 3 contains many Multibus board numbers. -- 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

27 years, 3 months

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Sun 1 question

by Innfogra＠aol.com

How can I identify Sun 1 cards? Paxton

27 years, 3 months

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The Paxton auction: any interest in rescues

by CLASSICCMP＠trailing-edge.COM

>Andromedia Systems Dual 5 1/4 floppy disk drive, DDMDS-B, SN 21. Could this >be for DEC equip. Almost certainly. Does it have a 34-pin connector on the back? Some of the Andromeda controllers took a "breakout board" that separated the floppy signals from the hard disk signals, but the pre-breakout-board cable was (AFAIK) always wider than 34 pins. Tim.

27 years, 3 months

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driving prices down?

by yakowenk＠cs.unc.edu

I just had an idea. One of the things pushing up e-bay prices is the publication of the high bids of past auctions. The logic for sellers is something like, since the previous one sold for this much, I should expect at least as much for this one. What if we kept (and publicized) a record of asking prices for the things that did *not* sell? Maybe buyers would look at that, and use similar logic to avoid bidding any higher than that? Bill.

27 years, 3 months

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Connecting CSA's Transputer Education Kit to an Inmos B008

by rmeenaks＠olf.com

>> >> Hi, >> >> I have several B004-style CSA Transputer Education Kits (aka TEKs) that use >> an 8-pin minidin connector for its link (compatible to apples printer >> cables). Is there any way for me to connect these nodes to an inmos B008 >> motherboard's 37-way external connector?? Thanks. > > >If they're standard Transputer links, then sure. Have you tried tracing >the pins on the 8 pin miniDINs to see what they're connected to (like >link pins on the transputer)? Reset/error/analyse could be harder to >trace (since they'll possibly go to PALs), but you should be able to >figure something out by which are inputs/outputs. > Actually, I have full details on how to connect (with pinouts) TEKs to other transputer motherboards including INMOS', but not the INMOS B008. Apparently, the specs mention a 5x1 connector (or is it a 5x2) on inmos boards that can be used to connect the TEK to, but since I don't have a B008 yet (coming in the mail anytime now), I can't verify if this type of connector exists on it. I will send out full details once I am at home with all the pinouts etc. Ram

27 years, 3 months

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1802 data sheets: was old data books

by CLASSICCMP＠trailing-edge.COM

>Speaking of which, sometime back I failed to convince a surplus to sell >me a really old RCA databook which contained information on the two-chip >predecessor of the 1802, which went by the numbers CDP1801R and CDP1801S >if memory servers. > >Anyone have the book or data sheets? I'd love to get copies. Hmm, this doesn't help you much, but I did a bit of poking around, and here's what I came up with: Harris, the current producer of the 1802, has the following documents online: Application notes: AN6565 Design of Clock Generators for Use with COSMAC Microprocessor CDP1802 http://www.semi.harris.com/data/an/an6/an6565/ CMOS CPU Data sheets: CDP1802A \ CDP1802AC| http://www.semi.harris.com/data/fn/fn1/fn1305/ CDP1802BC/ High-Reliability 8-bit CMOS Processor data sheets: CDP1802AC/3 http://www.semi.harris.com/data/fn/fn1/fn1441/ I briefly paged through the above data sheets to see if they might have file numbers for any of the 1801 data sheets, but didn't see any. It was interesting to see that at least some of these classic parts are now available in PLCC's (I suppose this is the modern equivalent of the Flat-Pack, roughly speaking.) If you want to continue the search further, Harris has online data sheets for much of the CDP18XX series (including the classic 1802 interface and memory parts), and maybe one of these will have a file number for an 1801 data sheet. After you get a file number, you can usually have the folks at Harris fax the data sheet to you. -- 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

27 years, 3 months

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Repairing core

by ethan_dicks＠yahoo.com

--- Bill Yakowenko <yakowenk(a)cs.unc.edu> wrote: > So what kind of wall hanging is more appropriate for a geek? I have, mounted on a board over the door, a slide rule entitled "In Case Of Emergency". It was my father's when he was in college. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com

27 years, 3 months

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

by allisonp＠world.std.com

<One plastic box is labeled "Univac memory elements" and has a small sample <of 3 size cores. The largest is about 1mm O.D. and the smallest is less <than half that size. They look very fragile as the I.D. is almost as large <as the O.D. Those are about the size of the 8E cores. <The other is a "Indiana General 15 mill memory plane" I guess the cores ar <15 mill diameter. There are 16 cores wired as a 4x4 plane. The wires are Big fat ones... not really. Those planes would be easy to drive and understand. that would be one I'd love to try. <much smaller than 30 SWG (about 28 AWG). I would say much smaller than 50 <(either) gauge, I need a magnifier just to see them. I'd have guessed thinner than #40. Allison

27 years, 3 months

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

by pete＠dunnington.u-net.com

On Apr 20, 16:04, Chuck McManis wrote: > I'm not sure I parsed this. At my local hardware store the nuts were made > of Zinc (not steel) and but the washers were made of "soft iron" which I > thought meant there was a _lower_ carbon content than "steel" washers. (The > washers are designed to be compliant whereas the nuts are quite hard) Zinc isn't a hard metal and it's only weakly ferromagnetic (doesn't stick to a magnet). The nuts you found are zinc-plated steel, probably what we call BZP (bright zinc plated). Soft iron sometimes has quite a high carbon content, and a very variable silicon content (which affects its magnetic permeability). The composition of "soft iron" varies quite a lot, whereas although different types of steel have different compositions, the composition of any given type is fairly standard (and in some cases very precisely controlled), and usually quite low in silicon. -- Pete Peter Turnbull Dept. of Computer Science University of York

27 years, 3 months

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z80 timing... 6502 timing

by yakowenk＠cs.unc.edu

On 19 Apr 1999, Richard Erlacher <edick(a)idcomm.com> wrote: ] It's true that may be more interesting when you have different vehicles, but ] if you're trying to determine which of two is faster, don't you focus on ] those two? Having lots of variations in the hardware only tends to muddy ] the water. Obviously, some of us care about vehicles other than those two. Doesn't muddy _my_ waters one bit. :-P I, for one, am interested in processor capabilities independent of video/disk/etc gorp. Roman numerals isn't going to be a thorough comparison, but it's better than nothing, and small enough to be fun. If this is still going on in a month or two, maybe I'll write an entry myself. As it is now, my schedule barely allows me to keep up with all the stuff you guys are writing! And then, later the same day, regarding my suggestion about noting the relative ages of processors when comparing their results, he wrote: ] It's pretty hard to imagine how a limitation like your suggestion would ] apply. Newer processors addressed weaknesses in the older ones. One of ] those was ease of programming. In some cases, e.g. the 6809, the processor ] was designed with a regular instruction set and lots of addressing modes so ] as to make generating code easy. It didn't necessarily make it faster. I ] don't know how elegant such code will ultimately turn out to be. If you want to get a handle on which processors were really better than others performance-wise, you look at the best they can do on some specific problems. Granted, the results may not be easy to interpret because of varying environmental characteristics. Welcome to Earth. Nothing is simple here. Obviously, if the 6809 loses to some older processor, its adherents can still claim ease-of-coding as a benefit. But it would still be interesting to know if it could regularly get whomped by a measly, pathetic, sad-excuse-for-a-processor like the 6502. :-) :-) :-) :-) My suggestion was not meant as any sort of limitation, just my take on what kind of result would be interesting; one way of interpreting the results. If an older processor doesn't do as well as the newer one, well, we expected that. But if an older one outperforms a newer one, there is something worth exploring there, a lesson to be learned about an improvement really wasn't. Bill.

27 years, 3 months

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Has anybody heard from Wirehead?

by bill＠chipware.com

Hate to use the list for this purpose but he doesn't seem to be responding to any email lately. Does anybody know why? Thanks, Bill Sudbrink

27 years, 3 months

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Semi OT: Twitching Mac pointer

by healyzh＠aracnet.com

Has anyone ever seen a pointer on a Mac start to twitch? Mine seems to have started jiggleing back and forth slightly. Really disconcerting. Any ideas on if this is the mouse, or the machine :^( It seems to have something to do with how the cord is twisted, so I'm suspecting that the wires are getting a little frayed :^( When I smooth the cable out, it seems to stop. 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/ |

27 years, 3 months

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DEC BC11A-15 Cable

by danburrows＠mindspring.com

>Am I correct that this is used to connect the UNIBUS backplane in one >chassis to a UNIBUS backplane in another chassis? Yes. Do you need any? I have several different lengths here. The -15 is the length in feet IIRC. Dan

27 years, 3 months

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heads up; OSI Challenger 1P

by allisonp＠world.std.com

<I would call 115V 30A a common business circuit; it's certainly exceedingl <common on minicomputer power controllers. What else do folks plug the <Twist-N-Locks on their DEC 861C power controllers into? Special. Most places where I've seen systems installed for the first time that circuit had to be added. Even at DSG, PK3 and the Mill I had to have facilities add circuits for some things as that was not the normal distribution in the lab areas. My reference was that the average business and building unless prepped will only have 15 or maybe 20A outlets in place. Older buildings those will be in short supply. Then again NYC is where I have most of that experience. Allison

27 years, 3 months

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

by allisonp＠world.std.com

<generator set up to drive a fast rise time buffer amp (so I can get a <reasonable amount of current) what else do I need to do to verify that I'v <successfully "flipped" the device. (My first guess would be a garden <variety compass) first you need a waveform that looks like this.... _____|-----|_____________ _______+I |_____| -I And put about one turn through the ferrite or steel under test. Then you'll need a second 1-2 turn loop hooked to the scope. You'll know the right waveform when the signal starts showing a huge amplitude difference as switches. Allison

27 years, 3 months

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Power connectors

by danburrows＠mindspring.com

>First, to get common names: >Hot = one Phase >Neutral = Protective Ground >Ground = Ground (the starpoint on 3 phases connected to earth at the 'generator') That explains the confusion. In the US: Hot is one phase and in single phase systems you can and do have 2 hots. Neutral is what you are refering to as ground. The starpoint for both single and 3 phase. Ground is the protective / frame ground. The protective ground (ground in US codes) is not allowed to normally carry any current. It should be able to be temporarly disconnected and not create a hazardous condition. >Second, do I understand that US appliances got fuses on both wires >and both are switched ? On 240 volt equipment yes. The 120 volt plugs are defined with distinct Hot, Neutral and ground pins. I am familiar with your plugs also and have wondered how hot / neutral definitions are handled. Think of US 120V plugs like UK plugs just smaller and without fuses in them. >Over here in Germany only one wire is >switched and protected with a fuse, althrough it is not defined >which one is the 'hot' line, since our connector is symetrical >- there is no way to insert the plug in a way where the Hot and >the Ground side is defined - Our plug isn't inherited from the >DC times, but rather a new design when 220V AC became standard >in the 30s, to fit the needs of (and only of) AC Eq. The US did not used to make a distinction between hot and neutral until about 30 years ago when they added the "protective" ground pin. Now they are keyed. If you look closely at a receptacle, one blade is wider - neutral, The narrower blade is Hot and the round pin is protective ground. Some "equipment" uses only 2 wires. The blades and often one is larger to assure that it is polarized correctly. These polarized plugs have come into common usage in the last 20 years. Dan

27 years, 3 months

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Power connectors

by Philip.Belben＠pgen.com

>> >First, to get common names: >> >Hot = one Phase >> >Neutral = Protective Ground >> >Ground = Ground (the starpoint on 3 phases connected to earth at the >> 'generator') > >> That explains the confusion. In the US: >> Hot is one phase and in single phase systems you can and do have 2 hots. >> Neutral is what you are refering to as ground. The starpoint for both >> single and 3 phase. >> Ground is the protective / frame ground. Yes. In the UK, "Hot" is usually referred to as "Live", and until 1992 this was the official term. In 1992 the term was changed to "Line", so that the phrase "Live parts" could be introduced to mean any conductor connected to the electrical supply (i.e. not including the protective ground, which is called "Earth") >> >Second, do I understand that US appliances got fuses on both wires >> >and both are switched ? >> On 240 volt equipment yes. > > Ahh ja - we also use fuses in each 'Hot' wire - so if you have a > 3~ installation, 3 fuses are to be installed _and_ they have to > be tied (mechanical), so if one blows all 3 will go off. In the UK it is similar, although I don't think there is a requirement for fuses to break all three phases for a fault on one. Since the US has many 240V centre-tapped-to-ground installations, 240V would have fuses in both lines (both hot) but none in neutral. ISTR the neutral wire in some 240V equipment (cookers are an example that springs to mind) is used instead of protective ground, which makes me a little uneasy. >> >Over here in Germany only one wire is >> >switched and protected with a fuse, althrough it is not defined >> >which one is the 'hot' line, since our connector is symetrical >> >- there is no way to insert the plug in a way where the Hot and >> >the Ground side is defined - Our plug isn't inherited from the >> >DC times, but rather a new design when 220V AC became standard >> >in the 30s, to fit the needs of (and only of) AC Eq. Hans, I think you've gone some way to answering your own question here. See below. >> The US did not used to make a distinction between hot and neutral until >> about 30 years ago when they added the "protective" ground pin. Now they >> are keyed. If you look closely at a receptacle, one blade is wider - >> neutral, The narrower blade is Hot and the round pin is protective ground. >> Some "equipment" uses only 2 wires. The blades and often one is larger to >> assure that it is polarized correctly. These polarized plugs have come into >> common usage in the last 20 years. Ah. That explains some sockets that I saw when over there last year. > Strange, but common - I don't know any reason why the system has > to be keyed, I always assumed the US development of keyed plugs > was triggered by old DC systems (since in DC Eq. it is necersarry > to know the orientation), but not a new addition. Strange, we > dropped all orientationwhen switching to AC (with Protective > Ground). Could anyone give give a reason why the system has > to be keyed _IF_ a Protective Ground is included (other than > define the Protective Ground pin) ? Because, without Protective > Ground a definition of Neutral is essential, but with, no longer. Because the fuse and/or switch _in the equipment_ has to be on the hot/live side of the supply. Otherwise a blown fuse - because of a short circuit - could leave the equipment with the hot supply still connected to whatever shorted out. Which could be the chassis... Also, at least in the UK, some old equipment had neutral solidly bonded to the chassis and no protective ground. This is common on valved (tubed) radios and things. ISTR that here the fuse was generally on the chassis side, so that when the fuse blew, the chassis would no longer be connected. Still not really safe, since the chassis would be connected to the other side via the heaters of all the valves, and these typically pass 100mA to 300mA at mains voltage, or more if they're cold. Philip.

27 years, 3 months

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heads up; OSI Challenger 1P

by CLASSICCMP＠trailing-edge.COM

><>that were clearly under 1.4kw. The codes are aimed at providing reasonabl ><>power. Here a 15A/115v is the nominal and 115V/20A is a max >< ><No, it isn't. I have several 115V 30A circuits in my computer room - ><this being an extremely common rating on the power controllers used ><in smaller DEC systems - and looking at the codes and the Hubbell catalog ><it would seem that 60A circuits are standard things as well. >I should have qualified that as common residential and business circuits. I would call 115V 30A a common business circuit; it's certainly exceedingly common on minicomputer power controllers. What else do folks plug the Twist-N-Locks on their DEC 861C power controllers into? -- 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

27 years, 3 months

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heads up; OSI Challenger 1P

by danburrows＠mindspring.com

Be carefull doing this. All foreign 240 mains that I have worked with have been 240 between hot and neutral. This works out to be 416 phase to phase on 3 phase systems. What you will be doing is 240 between 2 hots. This can and will cause problems with a lot of supplies that expect the neutral to be at / near ground. I have several isolation transformers that I use for all the UK equipment I service and they all are wired for 240 Hot to neutral output. Also be careful what electrician you get to set it up for you. I have seen plenty of them manage to wire them wrong. I have even had to explain to them how to wire a buck / boost transformer only to have them fuse it for isolation ratings. >Here's how I'm avoiding this problem for my collection: I'm moving into a >new house and getting 220 installed where my stuff it going to be >located.. since it's right where the breaker panel is, it's not going to >cost much at all... so if the computer in question is going to be located >in a basement or wherever the breaker panel is, you don't even need a >transformer... just get an electrician, friend, or do it yourself.. > >Kevin >

27 years, 3 months

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Power connectors

by steverob＠hotoffice.com

> First, to get common names: > Hot = one Phase > Neutral = Protective Ground > Ground = Ground (the starpoint on 3 phases connected to earth at the 'generator') > Hot and Ground are the basic wires to tap power, Wrong... HOT and NEUTRAL provide the power legs. Earth Ground is only for protection and does not carry any power. The power company generates three phase because it is more efficient. However, in most residential areas they only provide a single phase. It doesn't make economic sense for them to string three wires when a single phase will suffice. The single phase (high voltage) is fed into a simple center tapped transformer where it provides 240 VAC for high power appliances and 2-phases each with 120 VAC for lighting and general use. || <---------- 120 VAC (HOT) ----------> || < > || < HV > || <---------- Neutral > || < ----------> || < || <---------- 120 VAC (HOT) In the early days, it was common for manufactures to use the device chassis or frame as a conductor. They would tie the Neutral wire to the chassis (under the assumption that the potential was near 0V) and save a few pennies in the manufacturing process. The problem was, it was possible to put the plug in the socket upside-down. This meant the chassis was tied to the hot leg and you could get electrocution just touching the device. In the 50's and 60's it was quite possible to get shocked by your TV by just turning it on! Today, most devices have polarized plugs so that can't happen. The neutral line should NEVER be fused. If that fuse happened to blow and the one on the HOT(s) leg didn't, the device would still be hot (even with a blown fuse). This would cause an unsafe condition. Steve Robertson - <steverob(a)hotoffice.com>

27 years, 3 months

5
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heads up; OSI Challenger 1P

by danburrows＠mindspring.com

>Tony wrote: >> No. The US mains is 234V centre-tapped. It's not part of a 3-phase system >> (at least not normally) > >Except in the sense that the incoming "single phase" power is derived >from two out of three phases somewhere higher up in the distribution >hierarchy. The utility company doesn't generate different "single phase" >power for residential customers. It is taken from 1 hot (13 to 14KV) of the 3 phase grid. Dan

27 years, 3 months

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