October 2005 - test-drb@ccmp.vtda.org

by dbetz＠xlisper.mv.com

I've made a bit of progress with my new 11/73 (got a prompt from console ODT), but I found a problem. One of the power supply fans is dead. Anyone know where I can get a replacement fan for the H7861 power supply? Thanks, David

20 years, 7 months

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IBM 5110&In-Reply-To=

by RHILL＠bountifulutah.gov

I have an old 5110 and 5120 system, also. Did you find any interested buyers? Please let me know. Thanks so much. Ralph Hill

20 years, 7 months

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Fan Direction (was: Re: PC floppy cable twists...)

by ajp166＠bellatlantic.net

> >Subject: Fan Direction (was: Re: PC floppy cable twists...) > From: Mark Tapley <mtapley at swri.edu> > Date: Fri, 21 Oct 2005 13:24:57 -0500 > To: cctalk at classiccmp.org > >At 6:09 -0500 10/21/05, Allison wrote: >>.... All of my systems >>cooling and air flow get attention even if it requires some card stock >>and tape duct work. Fans blow in and filters keep cat hair and >>other deutrius from getting in those places where it's going to do bad >>things. I find that tends to keep the inside of my PCs clean too. I >>turn the fan around and add a filter. Beats having a hairball clogging >>the cpu fan and crashing the system. > ><see my previous posting, somewhere back in the archives...> > Although this in general is a good idea, it doesn't always >work. NeXT cubes were designed with the fan exhausting air, so the >crapola sucked in through the optical drive slot wiped out the >optical drive before long. NeXT eventually approved the procedure to >mechanically turn the fan around (do *NOT* simply reverse the >connector). That would be a bad thing. > Problem is the designers actually did do _some_ thinking. On >its way out the fan in the original configuration, the air went over >the logic board(s) first, then the power supply and drives last. >Reverse the fan, it's now hot air hitting the logic board. On my >system, this caused the SCSI controller to fail occasionally. > Solution in my case was to put the fan back to its original >configuration, then tape over the floppy and optical cut-outs on the >front of the case. (N.B. my system may be unique in that the floppy >is mounted with a custom mount to an optical-sized cutout, with no >attempt to seal well. It may be that either taping or reversing the >fan would have solved the problem.) >-- Before I did it there was some thought applied and a few changes like an added fan in a differnt location. In the end I was both pressurizing the case and insuring adaquate airflow over the hardware. In the case of most PCs the airflow pattern is at best bad and its difficult to make even small improvements. But some of the S100 cases the airflow was poor to non existant. In those trying to get a laminar airflow or even air to flow between the boards in a crowded case was hard to achive. The worst is any of the altairs, one look and you see why. Allison

20 years, 7 months

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Weird BiPolar ROM programmer

by rigdonj＠cfl.rr.com

I was out today and found an interesting looking box made by Aydin Controls. It looks like a BiPolar PROM programmer. It has two 8 pin ZIP sockets marked Read and two others marked Program along with several LED diplays (TIL 311s! :-) and a lot of switches and pushbuttons on it. It looks old so I decided to open it up and see what kind of microprocessor it had in it. However I couldn't find one! It has four AMD 2101 RAMs, twelve TIL 311 displays, a COM 2017 UART and a COM 5016 baud rate generator but everything else looks like standard 74xx TTL. I couldn't find anything that looked like ROM, PROM, EPROM or a CPU. Is it possible that this thing is all controlled by TTL logic? Has anyone ever seen anything like this before? FWIW most of the ICs are dated 1982 so I guess it that's when it was made. Joe

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by mjd.NO.bishop.SPAM＠iee.org

QUOTE The 8/A cannot have an EAE UNQUOTE Don't think this is correct. Because, such a machine would have no serious (integer) arithmetic capability. Also, the PDP 8/A Minicomputer Handbook 1976/77 has a lengthy section [pp9-56 .. 9-65] on the KE8-E (Extended Arithmetic Element : EAE). However, the "PDP-8 Summary of Models and Options" (posted by Doug Jones) indicates that the EAE can be fitted iff the PDP-8/E CPU boardset is fitted. That is PDP-8/A models 600/620 were fitted with the KK8E CPU and optionally the 8/E EAE. And, I imagine "field specials" were doubtless built. Another wrinkle; correction invited. Martin -----Original Message----- From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org]On Behalf Of Johnny Billquist Sent: 21 October 2005 12:00 To: cctalk at classiccmp.org Subject: Re: Wondering which OS to use (PDP-8/A) << snip >> Yes, as far as software is concerned, most everything written for an 8/I or 8/E will also run on an 8/A. << snip >> However, the 8/E and 8/A are *very* similar. In fact, some 8/A systems had the KK8E CPU in them. Things that are incompatible, as far as I can remember offhand right now: BSW instruction exists only on 8/E and 8/A. MQ register exists always on 8/E and 8/A, but only exists on 8/I if you have EAE. <<<<NB>>>> The 8/A cannot have an EAE. <<<<NB>>>> The EAE of the 8/E can run in two modes, where one is compatible with the EAE of the 8/I. If you execute a RAR RAL, you'll get different results depending on CPU. I don't remember exactly what the 8/I does, but the 8/E will load the AC with the PC for the high five bits, while the low seven will be fixed (can't remember the exact value). The 8/A will load the AC with the PC. << snip >>

20 years, 7 months

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Fan Direction (was: Re: PC floppy cable twists...)

by mtapley＠swri.edu

At 6:09 -0500 10/21/05, Allison wrote: >.... All of my systems >cooling and air flow get attention even if it requires some card stock >and tape duct work. Fans blow in and filters keep cat hair and >other deutrius from getting in those places where it's going to do bad >things. I find that tends to keep the inside of my PCs clean too. I >turn the fan around and add a filter. Beats having a hairball clogging >the cpu fan and crashing the system. <see my previous posting, somewhere back in the archives...> Although this in general is a good idea, it doesn't always work. NeXT cubes were designed with the fan exhausting air, so the crapola sucked in through the optical drive slot wiped out the optical drive before long. NeXT eventually approved the procedure to mechanically turn the fan around (do *NOT* simply reverse the connector). Problem is the designers actually did do _some_ thinking. On its way out the fan in the original configuration, the air went over the logic board(s) first, then the power supply and drives last. Reverse the fan, it's now hot air hitting the logic board. On my system, this caused the SCSI controller to fail occasionally. Solution in my case was to put the fan back to its original configuration, then tape over the floppy and optical cut-outs on the front of the case. (N.B. my system may be unique in that the floppy is mounted with a custom mount to an optical-sized cutout, with no attempt to seal well. It may be that either taping or reversing the fan would have solved the problem.) -- - Mark 210-522-6025, temporary cell 240-375-2995

20 years, 7 months

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Software for one Osborne Vixen

by dave04a＠dunfield.com

At 21:38 20/10/2005 +0200, you wrote: >Hello. I've received some time ago one Osborne Vixen. It's in working state. >I should like to obtain software for it, or even try with software for >previous versions of the Osborne portable family of computers. Are there >available in some place in the Internet disk images for it, or could someone >how own them send me a copy, please ? Off list to discuss the details, >please. Thanks. I have the Vixen system disks up on my site. Look in "Disks/Software images" near the end of the main page. Dave -- dave04a (at) Dave Dunfield dunfield (dot) Firmware development services & tools: www.dunfield.com com Collector of vintage computing equipment: http://www.parse.com/~ddunfield/museum/index.html

20 years, 7 months

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Replacing Old LEDs (Bradley Slavik)

by dwight＠ca2h0430.amd.com

>From: "Barry Watzman" <Watzman at neo.rr.com> > >Excluding odd LEDs (like your 12 volt model which, again, is probably a >low-voltage LED with the resistor built-in probably for automotive use), any >LED will work, although different ones will vary in brightness and power >consumption (if power consumption matters .... usually it does not). If you >get it backwards, it won't light, but no harm will be done. > Hi Barry This is not really true. If driven from a 5 volt source, you are right, no damage. I once had to replace a number of LEDs that failed because of being reversed for part of the time. These were a simple connection to a 12vac line with a current limit resistor. They would light OK at first but degrade over about a week. I placed a diode across the LED to bypass the back voltage and there were no more failures. They tend to zener at around 10 volts someplace and are not happy being zeners. The power dissipated was small but there was some other effect of them acting a zeners that degraded them. Dwight

20 years, 7 months

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Big dollars paid for Altair 8800 on Ebay

by rigdonj＠cfl.rr.com

At 06:51 AM 10/21/05 -0600, you wrote: >Take a look at item #8707485844 >http://cgi.ebay.ca/ws/eBayISAPI.dll?ViewItem&item=8707485844&rd=1&sspagenam e=STRK%3AMEWA%3AIT&rd=1 >which ended on Thursday. It went for USD $7,877.11 Isn't that amazing? JC Wren had one with a load of other classic computers and the high bid was only about $2100! for a supposedly serial number 3 unit, run up by bidders from Switzerland, the US and finally the UK. It had been heavily modified internally, with even a hard disk inside. >My question to all is that was the unit more valuable (because of the low serial number) than a later unit that had all of the original MITS cards, motherboard and powersupply? My experience with car collectors (Corvettes), is that a unit in stock factory condition is more valuable than one that has been heavily modified. IMO ALL of the Altairs have been modified since they were sold only as kits. Yes you COULD buy assembled one but MITs still took a kit and just assembled it for you. To my knowledge none of them were build on an assembly line. Even MITs changed parts and revised the boards frequently so even the basic kits weren't all the same. On top of that, the user had to buy or build their own memory and I/O cards and the like (everything except the CPU card and chassis) so it's virtually certain that no two Altairs were identical even when they were new. And some mods such as a bus terminator were mandatory in order to make them work. Then considering that these were leading edge technology at the time and that they were constantly being hacked on and upgraded by their owners I would expect all of the surviving ones to be very different. I expect that 3rd party cards vs original MITs cards would detract from their value but not to the extend that 3rd party mods would to a collector's car. I suppose a better comparision would be a 1930s Duesenburg or some other car that were ALL build to order and no two were the same. Joe ('70 Hemi SuperBird, '70 440 6-pak Dodge Challanger RT Convertible, '70 Plymouth Baracuda, '68 Dodge Charger ....) >I suppose the buyer is going to restore the original MITS cards as it was first available, or is he going to keep it intact as it was sold to him? It would be interesting (to me) to know peoples collecting philosophies about that. > > >Gary Fisher >Tristone Capital Inc. >This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this e-mail and destroy any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. Unless otherwise stated, opinions expressed in this e-mail are those of the author and are not endorsed by the author's employer. > > > >

20 years, 7 months

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Language for the ages

by ajp166＠bellatlantic.net

> >Subject: Re: Language for the ages > From: "Chuck Guzis" <cclist at sydex.com> > Date: Thu, 20 Oct 2005 12:41:26 -0700 > To: cctalk at classiccmp.org > >On 10/20/2005 at 2:51 PM der Mouse wrote: > >>>>>> PSHR R2 ; Push R2 onto the stack >>>>>> MVII 10,R1 ; Move 10 to R1 >>> Hmmm ... registers are numbered, and it's SRC,DEST format ... I'd >>> guess ne of the later PDPs like a PDP-10 or PDP-11. >> >>Not the 11; I know that, and the opcode names and syntax are all wrong. >>(On the 11, that'd be "mov r2,-(sp)" and "mov #10,r1" (DEC syntax) or >>"mov r2,*-sp" and "mov $10,r1" (Unix syntax, if I've remembered it >>right).) > >No prize yet. Hint: it's a microprocessor, not a mini (it's not the >IM6100 or LSI 11). > I'd either punt for 68k or 32000. Allison

20 years, 7 months

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Replacing Old LEDs (Bradley Slavik)

by Watzman＠neo.rr.com

LEDs are very generic components. All of the ones that you are talking about are almost totally interchangeable, except for the 12 volt one (which is probably a low voltage one with a built-in resistor .... no LED truly operates off 12 volts). An LED is still a diode. In the wrong direction, it doesn't conduct, and it also doesn't give off any light, but no harm is done. In the "forward" direction, usually run from a 5 volt supply, it would burn out (basically it would be a short-circuit) except that it will invariably have a current limiting resistor in series with it. Since the actual voltage across the LED is .7 to about 3 volts or so, depending on the LED, and the supply voltage is almost invariably 5 volts, the current limiting resistor determines the current drawn and the power consumed (and, as a consequence, how bright the LED is). Some LEDs are significantly more efficient (give off more light per milliwatt used) than others, the specs will tell you that, but again, in most applications you don't care about the power consumption (milliwatts), and the brightness is subjective. Excluding odd LEDs (like your 12 volt model which, again, is probably a low-voltage LED with the resistor built-in probably for automotive use), any LED will work, although different ones will vary in brightness and power consumption (if power consumption matters .... usually it does not). If you get it backwards, it won't light, but no harm will be done.

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by bqt＠Update.UU.SE

On Thu, 20 Oct 2005, Ethan Dicks <ethan.dicks at gmail.com> wrote: > On 10/21/05, charlesmorris at direcway.com <charlesmorris at direcway.com> wrote: > > Currently I don't have any other input device aside from the programmer's panel > > and the keyboard, so naturally I need something that can be booted from an > > RL02... > > You may or may not have an RL boot PROM in your KM8AA, but if you > don't, you can always key in the RL bootstrap by hand. I'm not even sure they exist. Anyone have boot roms for RL? > > Could I run OS/8? TSS/8? Many years ago I used to have access to a TTY timeshared to an 8/E running Edusystem 50 (TSS/8) and would like that "feel" again... > > Dunno about TSS/8 on an RL (probably no driver for anything newer than > an RF08), but certainly OS/8. One caveat - there is a different > driver for the RL01 and for the RL02. I myself have never used an > RL02 on an 8/a. An expensive configuration for a DECmate I was an > RL02, so I'm sure OS/78 supports it, but you might have to cherry-pick > your OS/8 version to go with a larger disk. Actually, any version of OS/8 will work fine. What you need is the device driver. And yes, there are two different drivers, depending on RL01 or RL02. Um, actually there are four different device drivers, since each exists both for use as the system device, and not. I'm using an RL02 with my PDP8, and have for ages. A few things might need patches as well as having the device driver. RESORC and PIP comes to mind. They have tables of device sizes, which might not have the RL02 in there... Johnny Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at update.uu.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

20 years, 7 months

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480z floppy lead

by williams.dan＠gmail.com

I checked back in the archives and could only find discussions, does anyone know the pin-outs of the external floppy drive. Dan

20 years, 7 months

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Xenix on the Acorn 32016

by gtoal＠gtoal.com

An update to the comments of last week: I retrieved my source listing of the linker for Panos last night, and buried in the middle of it was a commented-out section for handling object files from Xenix-32000. So I guess at some point Acorn was indeed looking at Xenix for that platform. I do sort of have a vague recollection of some involvement with Logica. I suspect this was one of those one-man projects where the only Acorn person involved was the manager. Maybe Dave Lamkin, or his boss whose name escapes me for now. (Mike someone?) By the way the Panos linker is 3/4in thick fanfold and quite a bit to scan. I guess I'll do it sometime but it's not a priority; I've been having much more fun recently scanning Edinburgh University documents detailing the operation of both the PDP9/15 systems, and the Interdata 74's. In recent weeks I've scanned the sources of an operating system for the Interdatas ("Legos") and a BIOS for an ICL 7502 remote job entry terminal which Edinburgh University managed to turn into a serviceable computer. Also the documentation for the High Level Assembler used on both these systems. (We already had the source of the assemblers, just no docs or predef files.) The Edinburgh collection is getting quite impressive. We also have recovered locally written operating systems for the PDP9 and PDP15, two O/Ses for PDP11s, Perkin Elmer 32bit, 68000s and of course the big one, EMAS for ICL29XX and IBM mainframe architectures of various flavours. ( http://history.dcs.ed.ac.uk/ ) Graham

20 years, 7 months

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Big dollars paid for Altair 8800 on Ebay

by GFisher＠tristonecapital.com

Steve Wrote: >Message: 12 >Date: Fri, 21 Oct 2005 07:53:28 -0700 (PDT) >From: steve <gkicomputers at yahoo.com> >Subject: Re: Big dollars paid for Altair 8800 on Ebay >To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> >Message-ID: <20051021145329.54055.qmail at web51610.mail.yahoo.com> >Content-Type: text/plain; charset=iso-8859-1 > >I find interesting the big dollars that IBM manuals >are going for (>$900) > >http://cgi6.ebay.com/ws/eBayISAPI.dll?ViewListedItems&userid=suetbandit&sor… I wonder who dkdkk is? He bought almost all of the IBM stuff (modules and manuals) and plunked down over 16,800 US$. He must be re-selling to the government <grin> Gary Fisher Tristone Capital Inc. This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this e-mail and destroy any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. Unless otherwise stated, opinions expressed in this e-mail are those of the author and are not endorsed by the author's employer.

20 years, 7 months

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Big dollars paid for Altair 8800 on Ebay

by GFisher＠tristonecapital.com

Hans, You make excellent points! I'd do the same thing as I'd be very interested in seeing what was on that hard drive and actually running the machine in it's final re-incarnation. But maybe I would put the new cards in an later serial number box for operating (like a nice Star Trek game or Supercalc) and put other original cards, PS, and motherboard in the serial number 3 case. But I only have one already later model modded 8800 and didn't have nine grand Canadian either! (Now if it was an IMSAI, that would be another story....except for the nine grand!) <grin> ---- EDITED ORIGINAL MESSAGE BELOW----- >From: "Hans Franke" <Hans.Franke at siemens.com> >Subject: Re: Big dollars paid for Altair 8800 on Ebay >To: "General Discussion: On-Topic and Off-Topic Posts" > <cctalk at classiccmp.org> >Message-ID: <43591700.32111.10A59295 at localhost> >Content-Type: text/plain; charset=US-ASCII > >Now, regarding your implication, yes, a nice like new car has it's value, >but then again, a special sub serie might even catch a higher price when >not shiny, and then there are modifications. Thing of a Shelby GT with >added race trim. that would definitly catch a better price than a regular >(already expensive) Shelby GT. > >Now, the above Altair could be compared again to a hot-rodded Model T. >Lager engine (Z80) added high performace stuff (Hard Disk) and so on. >Such a Car has a value in itself, and restoreing it to a factory like >version should be considered vandalism. > >> I suppose the buyer is going to restore the original MITS cards as it was >> first available, or is he going to keep it intact as it was sold to him? >> It would be interesting (to me) to know peoples collecting philosophies >> about that. > >Well, tough question. As for myself, I guess I would keep it the way >it is right now. THe usage, the add ons _and_ the fact that it's ser#3 >add together for a very unique exhibition piece. 'Restoring' it would >take away the life and history. > >Don't get me wrong, this isn't a 'do not touch' thing, unlike some >weired car collectors, who buy cars and let them rust on purpose, I >would go ahead and restore (if needed) the Altair to its last working >condition. Make it show room able, but don't take away it's history. > >If the original cards where available with the unit, I wouldn't put >them back in, but rather use as part of a proposed displa, maybe >mounted on a wall behind the unit. > >Gruss >H. >-- >VCF Europa 7.0 am 29/30.April und 01.Mai 2006 in Muenchen >http://www.vcfe.org/ Gary Fisher Tristone Capital Inc. This e-mail and any attachments may contain confidential and privileged information. If you are not the intended recipient, please notify the sender immediately by return e-mail, delete this e-mail and destroy any copies. Any dissemination or use of this information by a person other than the intended recipient is unauthorized and may be illegal. Unless otherwise stated, opinions expressed in this e-mail are those of the author and are not endorsed by the author's employer.

20 years, 7 months

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Replacing Old LEDs

by dwight＠ca2h0430.amd.com

Hi You shouldn't plug a LED into a curcuit backwards that can supply more than about 8 volts someplace. LED's zener at about 8 to 10 volts and the power dissipated is much higher when it zeners, even with a limiting resistor. If you get the RS ones that are individually wrapped, they usually have the polarity marked on the back of the package. You should be able to check the polarity with a meter by measuring the voltage from the unit. Just match the polarities. Dwight >From: "Bradley Slavik" <fire at dls.net> > >I believe that all these LEDs are on ISA or EISA cards, circa 1987. > >Let me be more specific now that I have gone to radio shack. > >In 5mm red LEDs they have > >12volt, 2.6v, 1.8v > >Here are web pages: > >http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-2 >09 >? > >5mm Red LED >$1.29 ?????Brand: RadioShack >Catalog #: 276-209 ?????Model: 276-209 > > >Availability On-line: In-stock In Store: Check availability >Phone: In-stock 1-800-THE-SHACK (1-800-843-7422) >(Pricing and availability may vary outside the contiguous 48 United States.) >Typical MCD is 1.5. Typical wavelength is 697mm. Size is T-1-3/4 or 5mm. Red >lens color. Viewing angle is 36?. 10mA (max). Typical Voltage is 2.0, with a >maximum voltage of 12.0V. Comes as package of 1. > >http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=276-0 >41 > >5mm Red LED >$1.29 ?????Brand: RadioShack >Catalog #: 276-041 ?????Model: 276-041 > > >Availability On-line: In-stock In Store: Check availability >Phone: In-stock 1-800-THE-SHACK (1-800-843-7422) >(Pricing and availability may vary outside the contiguous 48 United States.) >Typical MCD is 10. Typical wavelength is 700mm. Size is T1 3/4 or 5mm. Red >lens color. Viewing angle is 30?. Current is 28mA (max). Typical Voltage is >2.25, with a maximum voltage of 2.6V. Comes as package of 2. > >276-330 which is 1.8v does not seem to have web page available. > >Should I just put in the 12v one? And turn around if I get it wrong? or >use jumpers to test it before soldering? > >Bradley > > >

20 years, 7 months

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RL01 drive select plug and power supply questions

by ajp166＠bellatlantic.net

> >Subject: Re: RL01 drive select plug and power supply questions > From: Paul Koning <pkoning at equallogic.com> > Date: Fri, 21 Oct 2005 10:58:55 -0400 > To: cctalk at classiccmp.org > > Allison> Yes I do. However for a single user system the load is not > Allison> an issue. If your running a timeshare system such as RSTS > Allison> or RSX with more than one user then DHV11 sense as well. > >Not true. 9600 baud is 960 interrupts per second, on a character I/O >device. That's a big number for a PDP-11. Output will be >significantly less of a burden with a DH type output controller than >with other types -- even for just one active terminal. Depends somewhat on the OS. It dont know about you but most people can't type much faster than 100WPM (less than 10 chars sec). For RT11 it's mostly unimportant. For unix (the most sensitive to interrupt loading you _may_ care as a single user). > Allison> For most of my 11s four lines is the limit for what I can > Allison> seem to keep busy. Figure a user terminal, LA100 Printer > Allison> and serial line for modem or data line to another system. At > Allison> the extreme I've run two terminals for OSs that support that > Allison> but, I can only type on on at any instant. ;) > >Sure, if you're mostly doing editing, then the CPU burden of high >speed output may not be obvious. If you had an LN03 or similar >printer, you might see it more easily. An LA100, of course, isn't >much of a problem because it is quite slow. Actually printers are a bursty load (fill the buffer and go away) and I've found that in practice the faster you fill the buffer the better (high line rates or use a parallel interface). Actually try this config. 11/23B 256kW ram RL02 RX02 x2 DLV11j terminal lines at 9600 DUV11 running DDCMP (DECnet phaseIII at 19.2k) LPV11 (modifiedto match dataproducts interface) with LN01/LN01S 12ppm printer. Later the LN01S was replaced with a DLV11 (same address) and LN03. RSTS (later RSX) 3 users Typical task load was BASIC (modeling program for reliability), calc, Text editing (word-11) and edit and a cardfile database written in BASIC. Also we had preLAT software for the 11 to take local printing from the VAX. Performance was good enough that we used that over the VAX (line lengths limited us to 2400baud in our part of the mill). That saved the VAX for email via the DUV link or direct. Later the DLV11j was replaced with a DHV and there was no noticeable performace improvement. It was a strange config but it helped us develop, sometimes test and support the up and comming printing products. We later moved to a VAX750 and found it not much faster as a user perception. One of the strong points of the -11 is it's interrupt performance compared to a lot of other machines. Not to say there wasn't a point where the loading wasn't noticable just took a bit to get there. The users noticed the modeling program the most as it was heavy on the calculations, more ram and an 11/73 would have helped. Allison

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by ajp166＠bellatlantic.net

> >Subject: Re: Wondering which OS to use (PDP-8/A) > From: Johnny Billquist <bqt at Update.UU.SE> > Date: Fri, 21 Oct 2005 13:06:20 +0200 (CEST) > To: cctalk at classiccmp.org > >On Thu, 20 Oct 2005, Ethan Dicks <ethan.dicks at gmail.com> wrote: > >> On 10/21/05, charlesmorris at direcway.com <charlesmorris at direcway.com> wrote: >> > Currently I don't have any other input device aside from the programmer's panel >> > and the keyboard, so naturally I need something that can be booted from an >> > RL02... >> >> You may or may not have an RL boot PROM in your KM8AA, but if you >> don't, you can always key in the RL bootstrap by hand. > >I'm not even sure they exist. Anyone have boot roms for RL? There must be as DEC sold 8As and RL02s as multi user WPS systems (wps200 comes to mind). No idea what the underlying OS for WPS was. Allison

20 years, 7 months

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RL01 drive select plug and power supply questions

by bqt＠Update.UU.SE

On Thu, 20 Oct 2005, Allison <ajp166 at bellatlantic.net> wrote: > >Subject: Re: RL01 drive select plug and power supply questions > > From: David Betz <dbetz at xlisper.mv.com> > > Date: Thu, 20 Oct 2005 18:26:02 -0400 > > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > > > >Thanks for your reply. I guess I'm okay with power even if I leave in > >the DHV11 as it seems my BA11-N has been upgraded to a H7861 power > > Unless you need the IO I'd pull it anyway. The system will run cooler > and I doubt you have need for the lines. DHV11 is a MUX and you need > the chassis kit to break out all the serial lines. Most OSs for PDP11 > don't use it (system build time option) and the DLV11J is easier to use > and program. The DHV11 cannot be used for a console either. I think I'll slightly disagree with you here. While all you say is essentially true, the DLV11 is a tremendour burden on the system compared to the DHV11. So if you actually want to run serial connections to a machine, keep the DHV11, and don't use the console more than absolutely neccesary. Big difference between DMA and interrupts you know... Johnny Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at update.uu.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by bqt＠Update.UU.SE

On Thu, 20 Oct 2005, djg at pdp8.net wrote: > For multi user operating systems the only one that will run on your > hardware is Multos-8. The version that has been recovered doesn't seem > to operate well though. Huh? As I believe all copies of Multos actually comes from a distrubution I have, this is news to me. Multos works just fine on my PDP8 atleast. However, it won't be much for the original question on this thread, as Multos don't support the RL8A either... Johnny Johnny Billquist || "I'm on a bus || on a psychedelic trip email: bqt at update.uu.se || Reading murder books pdp is alive! || tryin' to stay hip" - B. Idol

20 years, 7 months

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OT: Language for the ages

by cclist＠sydex.com

Here's an interesting problem. Suppose you wanted to write an application for a manufacturing process that will, in all probability, run for the next 30 years. No direct control of the process itself is entailed (i.e., you don't need the program to operation valves or run motors), but you do need this program to compute manufacturing parameters for each customer. I/O requirements are very modest, mostly simple keyboard and display. What would you write it in? Clearly, you'd want to be independent of a particular software vendor, so the likes of Visual BASIC isn't an option. You'd also want to write in a language that isn't nearing obsolesence, nor one that's still evolving. "Niche" languages would be out of the question, as longevity could be a problem. So what would it be? My vote is for FORTRAN. Cheers, Chuck

20 years, 7 months

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Short review of $550 power cord plus a new SWTPC 6800

by ajp166＠bellatlantic.net

> >Subject: Short review of $550 power cord plus a new SWTPC 6800 > From: "Michael Holley" <swtpc6800 at comcast.net> > Date: Thu, 20 Oct 2005 19:18:38 -0700 > To: <cctalk at classiccmp.org> > >With all of this ragging on audio nut who spend obscene amounts of money on >wire, I decided to at a look. I don't know why we call them crazy, they >don't have 1975 computer running in the basement. > >The guy in the next office is in to high end audio. (Although he claims that >he is in the lower end of the people in his audio club.) I asked if he had >a power cord so I could take some pictures. He had a spare PS Audio xStream >Statement Power Cable, the 2 meter version lists for $550. This is 6 gauge >oxygen free copper with machined connectors. The cord has a ferrite >impregnated jacket. > >Here is my short review of the power cord >http://www.swtpc.com/mholley/MP_F/PS_Audio.htm If the sound doesnt improve is there a fee to decontaminate the plug of the outlet cruft? ;) >I took it home and hooked it up to my new custom case computer which also >cost me about $550. It is a modern 3 GHz Pentium that looks like a 1975 >SWTPC 6800. >http://www.swtpc.com/mholley/MP_F/MP_F.htm#NewCover Nice case. I need to work out a way to get the picture of my Altair-11 up. Whats an Altair-11 it's a old Altair 8800 case with a PDP-11/23 inside H780 PS, H9281AC 12 slot backplane and a RD52. Allison

20 years, 7 months

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Fan for DEC H7861 power supply?

by ajp166＠bellatlantic.net

> >Subject: Fan for DEC H7861 power supply? > From: David Betz <dbetz at xlisper.mv.com> > Date: Thu, 20 Oct 2005 22:38:02 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >I've made a bit of progress with my new 11/73 (got a prompt from >console ODT), but I found a problem. One of the power supply fans is >dead. Anyone know where I can get a replacement fan for the H7861 >power supply? > >Thanks, >David Memory test is; they are Rotron or equivelent 120V AC fans. Measure one and look it up on the net. FYI they push a fair amount of air. so any 120V fan that uses the same ac current and fits is likely a good match. Allison

20 years, 7 months

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: Re: PC floppy cable twists... > From: "Chuck Guzis" <cclist at sydex.com> > Date: Thu, 20 Oct 2005 17:54:49 -0700 > To: cctalk at classiccmp.org > >On 10/20/2005 at 8:41 PM Allison wrote: > >>Under those conditions I don't worry about my media unless its old >>and unknown. > >That's nice if you can make it happen, but I recall that our first >commercial installation of a 5.25"-equipped system was in a parking >garage... > >Cheers, >Chuck Well thats the challenge as an engineer. Good, Fast, Cheap, pick any two. Allison

20 years, 7 months

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Weird BiPolar ROM programmer

by ajp166＠bellatlantic.net

> >Subject: Weird BiPolar ROM programmer > From: "Joe R." <rigdonj at cfl.rr.com> > Date: Thu, 20 Oct 2005 20:48:10 +0000 > To: cctalk at classiccmp.org > > I was out today and found an interesting looking box made by Aydin >Controls. It looks like a BiPolar PROM programmer. It has two 8 pin ZIP >sockets marked Read and two others marked Program along with several LED >diplays (TIL 311s! :-) and a lot of switches and pushbuttons on it. It >looks old so I decided to open it up and see what kind of microprocessor it >had in it. However I couldn't find one! It has four AMD 2101 RAMs, twelve >TIL 311 displays, a COM 2017 UART and a COM 5016 baud rate generator but >everything else looks like standard 74xx TTL. I couldn't find anything that >looked like ROM, PROM, EPROM or a CPU. Is it possible that this thing is >all controlled by TTL logic? Has anyone ever seen anything like this >before? FWIW most of the ICs are dated 1982 so I guess it that's when it >was made. > > Joe I used to blast bipolar proms using switches and some ttl so yes it could be a simple sequential logic thing. Allison

20 years, 7 months

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PDP-8/A Front Panels

by v.slyngstad＠verizon.net

Charles Morris and I have been working to create an equivalent for the KC8A programmer's panel for the PDP-8/A. This panel uses modern parts where necessary, but follows the DEC design quite closely. The buttons and LED displays are larger, and it is designed to mount flush with the front of the PDP-8/A, where the original mounted to a beveled aluminum casting. Like the originals, there are two long, thin PCBs, held together with spacers, and affixed to a metal panel that attaches to the rack/8A. Charles has recently finished an awesome job of debugging the prototype (thanks, Charles!). (My job has been to drive the CAD tools and get the prototypes ordered and such.) Now he has the panel he needed to check out his 8/A :-). Now that we have (revised) CAD drawings and such for the front panel assembly, we are thinking about ordering boards for a "group buy", and want to see how much interest there is in these items. Unfortunately, the front panels are not inexpensive. It will cost us about $200 to place a PCB order(1), plus about $20 for each pair of boards (including the first one) ordered. Parts for each board pair run about $50. The metal panel is about $85 from Front Panel Express (which allows the panel to be mounted and look nice). In addition, there are costs associated with the prototype that we'd like people to help with, that are around $200. As you can see, the price is quite daunting for a single front panel: $220/1+$50+$85+200/3 = $422. Hence the attractiveness of a group buy. If we can order 5, then the cost each will be $220/5+$50+$85+$200/5 = $208. If we can order 10, then the cost each will be $220/10+$50+$85+$200/12 = $174. (That's under $100, if someone can make the metal panels :-).) I know there are many who don't have programmer's panels for their 8/A. So, are any of you willing to put up that kind of money to get one? Send me a mail with "I'd want one if the price gets to $xxx or less."(2). Thanks! Vince (1) We can't use an inexpensive prototype shop due to the boards' size: 15.5"x3.7". (2) I put up a lame page at http://so-much-stuff.com/pdp8/kc8a.html with some pictures of my prototype (not Charles' debugged one).

20 years, 7 months

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: Re: PC floppy cable twists... > From: "Chuck Guzis" <cclist at sydex.com> > Date: Thu, 20 Oct 2005 17:05:50 -0700 > To: cctalk at classiccmp.org > >On 10/20/2005 at 7:42 PM Allison wrote: > >>Media wear, I've had disks spinning for years in clean environments and >>several dead drives that were still fine. > >Dirt happens. It gets between the head and the media and doesn't do any >favors to either. I've got several diskettes in my collection that have >the oxide coating worn clear through on the directory track. Better to >either stop the motor or lift the head. Around here, during the driest >months of the year (August and Sepember), the clay soils turn to a very >fine powder and become airborne. Hoiuse dust during those months tends to >have a brownish color. > >Add to this that most PC's have fans on the power supply that are set to >exhaust air from the box, which means that the drive slot is a convenient >entry point for contamination. It used to be that fans were set blow the >other way and filters were used. That is a PCism. That being those fans that suck unfilterd crud and cruft into the system. In the summer we do get brown dust from whatever. All of my systems cooling and air flow get attention even if it requires some card stock and tape duct work. Fans blow in and filters keep cat hair and other deutrius from getting in those places where it's going to do bad things. I find that tends to keep the inside of my PCs clean too. I turn the fan around and add a filter. Beats having a hairball clogging the cpu fan and crashing the system. Under those conditions I don't worry about my media unless its old and unknown. Allison

20 years, 7 months

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: Re: PC floppy cable twists... > From: "Chuck Guzis" <cclist at sydex.com> > Date: Thu, 20 Oct 2005 16:02:43 -0700 > To: cctalk at classiccmp.org > >On 10/20/2005 at 6:23 PM Allison wrote: > > > >I think we're saying the same thing in different ways. If you don't have a >head load signal, the head remains in contact with the media the entire >time the media's in the drive. If the spindle is rotating, that leads to >head and media wear the entire time (althought he drive needs to spin a bit >to seat the media correctly when first inserted). If the motor's turned >off, no media wear, even though the head's still in contact. Nope not talking about media wear at all. I'm talking about the SA400/TM100 generation drives that used a brush type motor with belt drive that have a far shorter life than most of the halfheights that use a brushless direct drive pancake motor. The media wear is less an issue than the other problem with double sided drives. Clapping, those with head load solinoids (SA450 comes to mind) the head load/unload would not be gentle on the media. Thats why most later drives continiously load the head even when not spinning. >And yes, motors with brushes will fail with time. When I wrote my first >8085 diskette driver, I just turned the drive motors on at boot, having >come off an 8" floppy environment. I was admonished by a Micropolis >engineer that this was not a good idea and that the motor should be turned >on only when needed. So media was inserted into drives with the spindle at >a dead stop, leading to serious problems with seating the media. So drives >were modified to include a little spin-up when the drive door was being >closed. Not everyone did this gracefully, however, leading to wrinkled >areas around the media hub and so reinforcing rings were introduced. Actually testing showed that freqquent start/stops were harder on the motor to a certain point. It was the high current that would eventually wear the commutator. If you ran the motors the problem was they were not ball bearing and the bushing would wear and the brushes as well. >The interesting thing is the chicken-and-egg nature of this. Initially, >you didn't want to spin the media all of the time on a 5.25" drive because >the brushes in the DC motor would wear. So a motor control line was >incorporated. But then, if you could stop the media from spinning, you >didn't have to have a separate head-load mechanism to guard the meda and >the head against wear while not in use. there was a balancing act. Wearout for mechanical reasons and surge startup. The trick was keeping the drive running once accessed as it was likely you'd be back soon, if not time out. That lowered the start stop cycle wear and got you closes to the mechanical wearout limit. The later drives with direct drive motors and the like eliminated those concerns. Then powering down was power/heat savings. Media wear, I've had disks spinning for years in clean environments and several dead drives that were still fine. Allison

20 years, 7 months

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RL01 drive select plug and power supply questions

by ajp166＠bellatlantic.net

> >Subject: Re: RL01 drive select plug and power supply questions > From: David Betz <dbetz at xlisper.mv.com> > Date: Thu, 20 Oct 2005 19:02:24 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Mine is a KDJ11-A processor, RL01, RX50, RX02, MXV11-AC boot, 1.5mb >memory. I'm planning on running RT-11 and maybe Unix. I'd like to add >an RDxx drive. It looks like I'll have to find a different bootstrap >board to boot off of an RDxx though. Thats a strange config. Workable but strange. Allison

20 years, 7 months

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: Re: PC floppy cable twists... > From: "Chuck Guzis" <cclist at sydex.com> > Date: Thu, 20 Oct 2005 14:53:41 -0700 > To: cctalk at classiccmp.org > >On 10/20/2005 at 4:14 PM Michael B. Brutman wrote: > >>With all of those pins on the interface, why wouldn't the motors be >>independently controlled? That seems like a waste on any system, never >>mind the wear and tear on the drives & inserted floppies. > >But there really aren't any unused pins. Remember that all of the >odd-numbered pins are grounded, so that leaves only 16 for signals. Pin 2 >was originally reserved for "reduced write current" signalling (or "density >select'). Pin 4 was for "Head load" and was a spare only on some drives >that didn't have that feature and pin 34 was used for disk change/ready. >There really aren't any spares. > >Besides, with a "head load" facility, who needed to control the motors >individually? But the PC didn't use a drive with a head load facility... > >Cheers, >Chuck Once upon a time drive need time to spin up before you loaded the head and read it. As drives improved that time shortend and the motors went to brushless where relibility didn't degrade with stops and starts (brush motors this is a relability/wear issue). So having seperate motor enables allowed one to spin the drives and then allow a 10sec (or longer) timeout after last access before they would stop. Allison

20 years, 7 months

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RL01 drive select plug and power supply questions

by ajp166＠bellatlantic.net

> >Subject: Re: RL01 drive select plug and power supply questions > From: David Betz <dbetz at xlisper.mv.com> > Date: Thu, 20 Oct 2005 18:26:02 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Thanks for your reply. I guess I'm okay with power even if I leave in >the DHV11 as it seems my BA11-N has been upgraded to a H7861 power Unless you need the IO I'd pull it anyway. The system will run cooler and I doubt you have need for the lines. DHV11 is a MUX and you need the chassis kit to break out all the serial lines. Most OSs for PDP11 don't use it (system build time option) and the DLV11J is easier to use and program. The DHV11 cannot be used for a console either. >supply already. I'll consider getting an RQDX3 instead of the RQDX1. >Do you know if it uses the same cables to connect it with its drives? All the RQDXn controlers use the same cables. You will need the RQDX breakout board (either out of the BA23 or M9058 out of the BA123) to take the 50pin wide RQDXn to drive cables. >Actually, the only cable I have is to connect the RQDX1 to an RX50 >floppy drive. I'll need a cable to connect it to a hard drive at some >point. It seems that the RQDX3 cards are easier to come by than the >cables. I've seen many cards on eBay but never any cables. The cables are nothing special. Your missing the intermediate board that gors from the 50pin RQDXn to the 43pin that RX50 or RX33 uses and the 34/26pin comblo that common MFM hard disks used. Sounds like you have something like my 11/73. Mine is 4mb ram, RL02, RX33, (2)RD52 and RX02, serial is DLV11j. I run unix V6, Rt11XM and XXDP. Allison >On Oct 20, 2005, at 6:19 PM, Allison wrote: > >>> >>> Subject: RL01 drive select plug and power supply questions >>> From: David Betz <dbetz at xlisper.mv.com> >>> Date: Thu, 20 Oct 2005 17:28:56 -0400 >>> To: "General Discussion: On-Topic and Off-Topic Posts" >>> <cctalk at classiccmp.org> >>> >>> Does anyone have a spare RL01 drive select plug for drive "0"? I >>> recently acquired an RL01 drive (thanks Lyle Bickly and Jon Miles!) >>> but it's missing its drive select plug. This is one of the four >>> lights on the front of the drive that has the number "0" printed on >>> it for drive 0. Does anyone have one they're willing to part with? >>> >>> Also, the PDP-11/73 that I acquired is in a BA11-NC box. Does anyone >>> know how much power the power supply in this box can supply? There is >>> a list of the cards in the box and the power each one consumes and >>> I've inserted an additional card (an RQDX1 controller) that draws >>> 6.4A at 5V and I'm not sure that the power supply can handle it. That >>> would bring the total to 26.9A at 5V where the original total was >>> 22.3A. I could remove a DHV11 card that draws 4.3A to bring the total >>> down to 22.6A if necessary. What is save with this power supply? >>> >>> Thanks, >>> David >>> >> >> BA-11N +5 at 22A +12 at 11A max assumes H9273 mackplane and H786 PS >> >> I have a system that I subbed in a H7861 to the BA11N that PS is >> same size >> and form factor but +5 at 36A and +12 at 5A (typically found in BA11S). >> As most >> newer boards had a greater need for +5 than +12. >> >> If you don't need the serial lines then pull the DHV11. I've found >> running the supply right at the limit was not the best for >> reliability. >> >> Also the RQDX1 was not a very good version unless it was upgraded to >> RQDX2. the reason is it didn't support RX33, and the largest disk >> if memory serves for RQDX1 was RD52 (30mb quantum D540). RQDX2 >> supported >> the RD53(70mb) and RD54 (150mb). The RQDX3 supported more drives and >> is a bit lighter in current draw (RD31 and 32 plus RX33). >> >> ALSO the RQDX1 MUST BE LAST ON THE BUS. Many of the RQDX1 controllers >> lacked GRANT pass down. >> >> >> Allison >>

20 years, 7 months

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RL01 drive select plug and power supply questions

by ajp166＠bellatlantic.net

> >Subject: RL01 drive select plug and power supply questions > From: David Betz <dbetz at xlisper.mv.com> > Date: Thu, 20 Oct 2005 17:28:56 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > >Does anyone have a spare RL01 drive select plug for drive "0"? I >recently acquired an RL01 drive (thanks Lyle Bickly and Jon Miles!) >but it's missing its drive select plug. This is one of the four >lights on the front of the drive that has the number "0" printed on >it for drive 0. Does anyone have one they're willing to part with? > >Also, the PDP-11/73 that I acquired is in a BA11-NC box. Does anyone >know how much power the power supply in this box can supply? There is >a list of the cards in the box and the power each one consumes and >I've inserted an additional card (an RQDX1 controller) that draws >6.4A at 5V and I'm not sure that the power supply can handle it. That >would bring the total to 26.9A at 5V where the original total was >22.3A. I could remove a DHV11 card that draws 4.3A to bring the total >down to 22.6A if necessary. What is save with this power supply? > >Thanks, >David BA-11N +5 at 22A +12 at 11A max assumes H9273 mackplane and H786 PS I have a system that I subbed in a H7861 to the BA11N that PS is same size and form factor but +5 at 36A and +12 at 5A (typically found in BA11S). As most newer boards had a greater need for +5 than +12. If you don't need the serial lines then pull the DHV11. I've found running the supply right at the limit was not the best for reliability. Also the RQDX1 was not a very good version unless it was upgraded to RQDX2. the reason is it didn't support RX33, and the largest disk if memory serves for RQDX1 was RD52 (30mb quantum D540). RQDX2 supported the RD53(70mb) and RD54 (150mb). The RQDX3 supported more drives and is a bit lighter in current draw (RD31 and 32 plus RX33). ALSO the RQDX1 MUST BE LAST ON THE BUS. Many of the RQDX1 controllers lacked GRANT pass down. Allison

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by djg＠pdp8.net

> Now that I have an apparently functioning PDP-8/A with 16K of core, and > (hopefully soon) a working RL02, I am wondering what operating system > would be appropriate. Currently I don't have any other input device aside > from the programmer's panel and the keyboard, so naturally I need something > that can be booted from an RL02... > > Any recommendations? Will software written for, say, an 8/E or 8/I run on > an 8/A without patching? > >Could I run OS/8? TSS/8? Many years ago I used to have access to a TTY >timeshare d to an 8/E running Edusystem 50 (TSS/8) and would like >that "feel" again... The 8/A was compatible with the earlier machines so software should work unless they were requiring an option which isn't on the 8/A. OS/8 is your best bet. TSS/8 won't work with an RL drive. For multi user operating systems the only one that will run on your hardware is Multos-8. The version that has been recovered doesn't seem to operate well though.

20 years, 7 months

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PC floppy cable twists...

by julesrichardsonuk＠yahoo.co.uk

... discussion about this on another list got me curious - what *was* the point of that cable twist in a (IBM clone) PC floppy cable, when every other system on the planet was using straight-through cables? 1) Great, it means both drives in a system can be jumpered for the same ID - but someone's still got to go in and jumper/modify the last drive in the chain so that it's terminated, so it's not like the twist eliminates messing around with jumpers. 2) when the twist was introduced, there were presumably no clone machines around (it was there from day 1 IIRC) - and wouldn't the addition of a second floppy drive to an IBM machine have been a field service call anyway? So it's not like it was the general public changing jumpers, but a trained engineer... 3) IBM seemed to use a very small range of drives in the PC / XT / 286 days, so it's not like there'd be a million jumper combinations to figure out. If a customer tried to add their own drive rather than buying through IBM, surely IBM couldn't care less if they struggled to figure the drive jumpers on their 'non-standard' unit out? It's got me curious as it seems like a hack that doesn't completely solve any kind of problem whilst introducing a difference between IBM and the rest of the industry. cheers Jules

20 years, 7 months

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PC floppy cable twists...

by mbbrutman＠brutman.com

For the longest time I was stumped about how to get four drives onto a PC 5150. The BIOS supports it, but looking at the cable it just shouldn't work. There was the twist to control drive select and the one motor line - that's not enough to control four drives. I started kicking myself really hard when I rememberd that the other two drives had to go on the external cable, which has it's own motor and drive select line ... Still, mapping out the PC floppy cable compared to other systems was interesting. Even compared to an AT it is different. The AT supports a high density signal line on a previously unused pin. The other systems looked like they had independent drive select lines, but as somebody else pointed out, the motors all ran at the same time. With all of those pins on the interface, why wouldn't the motors be independently controlled? That seems like a waste on any system, never mind the wear and tear on the drives & inserted floppies. Mike

20 years, 7 months

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Replacing Old LEDs

by fire＠dls.net

Dear Classic Computers, I regret that my EE knowledge was never deep and is a little rusty now. I am refurbishing some old PC boards and wanted to replace a few of the LED which had become damaged or broken off. Here is my lame question, how do I correctly pick replacement LEDs? I know colors, and size, but how do I make certain that I have picked correct wattage, etc.? If some one with more experience could provide a few sentences of guidance I would be grateful. I can even put a Tektronix scope on it and take measurements if necessary. Bradley Slavik

20 years, 7 months

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RL01 drive select plug and power supply questions

by dbetz＠xlisper.mv.com

Does anyone have a spare RL01 drive select plug for drive "0"? I recently acquired an RL01 drive (thanks Lyle Bickly and Jon Miles!) but it's missing its drive select plug. This is one of the four lights on the front of the drive that has the number "0" printed on it for drive 0. Does anyone have one they're willing to part with? Also, the PDP-11/73 that I acquired is in a BA11-NC box. Does anyone know how much power the power supply in this box can supply? There is a list of the cards in the box and the power each one consumes and I've inserted an additional card (an RQDX1 controller) that draws 6.4A at 5V and I'm not sure that the power supply can handle it. That would bring the total to 26.9A at 5V where the original total was 22.3A. I could remove a DHV11 card that draws 4.3A to bring the total down to 22.6A if necessary. What is save with this power supply? Thanks, David

20 years, 7 months

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Wondering which OS to use (PDP-8/A)

by charlesmorris＠direcway.com

Now that I have an apparently functioning PDP-8/A with 16K of core, and (hopefully soon) a working RL02, I am wondering what operating system would be appropriate. Currently I don't have any other input device aside from the programmer's panel and the keyboard, so naturally I need something that can be booted from an RL02... Any recommendations? Will software written for, say, an 8/E or 8/I run on an 8/A without patching? Could I run OS/8? TSS/8? Many years ago I used to have access to a TTY timeshared to an 8/E running Edusystem 50 (TSS/8) and would like that "feel" again... thanks Charles

20 years, 7 months

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anyone have a DEC RA82 service manual?

by jdrcpeterson＠graceba.net

Anyone have a DEC RA82 service manual? Darren Peterson

20 years, 7 months

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: Re: PC floppy cable twists... > From: "Teo Zenios" <teoz at neo.rr.com> > Date: Thu, 20 Oct 2005 14:51:46 -0400 > To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at classiccmp.org> > > >----- Original Message ----- >From: "Allison" <ajp166 at bellatlantic.net> >To: <cctalk at classiccmp.org> >Sent: Thursday, October 20, 2005 2:35 PM >Subject: Re: PC floppy cable twists... > > >> >> You missed the most basic reason. One part, one bin, one stocking number >> and less standing stock. Logistics of warehousing costs and space not >> electrical design. >> >> Everyone seems to forget or even miss that not too long after the PC was >> introduced and clones appeared the costs of producing, stocking and >servicing >> them were under great pressure. Anything that cost, even pennies, could >put >> a vendor at risk. Why did some vendors disappear? >> >> >> Allison > >The original clone makers still had a huge profit margin so a few pennies >would not have mattered until the huge 1989-91 shakeout where pretty much >everybody started competing on nothing else but price (and purchasing power >benefits). I remember advertisements (early 90's ?) where DELL was comparing >its server to Compaq and it was thousands less for the same spec machine. But it did matter. It was only a matter of time that some vendors that were bleeding from the eyes tossed in the towel or were gobbled up. one of the major steps was to move to offshore production to reduce product costs. >From inside the industry it was already apprent by the late 80s that costs were under pressure. The clone companies often had a great advantage as they were smaller and less burdened than IBM, DEC and others. By '91 some were already dead or dieing. Allison

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PC floppy cable twists...

by ajp166＠bellatlantic.net

> >Subject: PC floppy cable twists... > From: Jules Richardson <julesrichardsonuk at yahoo.co.uk> > Date: Thu, 20 Oct 2005 17:48:04 +0100 > To: General Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org> > > >.... discussion about this on another list got me curious - what *was* >the point of that cable twist in a (IBM clone) PC floppy cable, when >every other system on the planet was using straight-through cables? > >1) Great, it means both drives in a system can be jumpered for the same >ID - but someone's still got to go in and jumper/modify the last drive >in the chain so that it's terminated, so it's not like the twist >eliminates messing around with jumpers. Jumpers were not messed with. Drive arrived, plugged in and go. Cost of delivering service was by then high enough that giving the drive away to avoid the call was actually becomming loss avoidence! >2) when the twist was introduced, there were presumably no clone >machines around (it was there from day 1 IIRC) - and wouldn't the >addition of a second floppy drive to an IBM machine have been a field >service call anyway? So it's not like it was the general public changing >jumpers, but a trained engineer... There was no jumper change. All had pullups and they are sized to allow two in parallel without problems. >3) IBM seemed to use a very small range of drives in the PC / XT / 286 >days, so it's not like there'd be a million jumper combinations to >figure out. If a customer tried to add their own drive rather than >buying through IBM, surely IBM couldn't care less if they struggled to >figure the drive jumpers on their 'non-standard' unit out? 2 is greater than 1. Cost to stock two is greater than one. >It's got me curious as it seems like a hack that doesn't completely >solve any kind of problem whilst introducing a difference between IBM >and the rest of the industry. > >cheers > >Jules You missed the most basic reason. One part, one bin, one stocking number and less standing stock. Logistics of warehousing costs and space not electrical design. Everyone seems to forget or even miss that not too long after the PC was introduced and clones appeared the costs of producing, stocking and servicing them were under great pressure. Anything that cost, even pennies, could put a vendor at risk. Why did some vendors disappear? Allison

20 years, 7 months

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OT: Tube Audio

by ajp166＠bellatlantic.net

> >Subject: OT: Tube Audio > From: lee davison <leeedavison at yahoo.co.uk> > Date: Thu, 20 Oct 2005 17:02:33 +0100 (BST) > To: cctalk <cctalk at classiccmp.org> > >> I didn't say nonexistant, only rare. Dynaco was amoung the best >> then. The alternate was a filiment that was balanced to ground to >> minimize the amplitude of AC heater to cathode coupling, also only >> seen on quality gear. > >Another, rarer, alternate used with directly heated cathodes is to >have two cathodes heated by a Scott wound transformer that gives >two phase AC current with a 90 degree phase difference. This >reduced heater generated noise because the noise is a function of >the square of the heater voltage and sin^2 + cos^2 = 1, effectively >a DC component. > >I have only ever seen this arrangement used on broadcast equipment. > >Lee. The other technique is far simpler. Balance, do the same thing only in mirror image. The reduction in hum and some types of noise is substantial and tube engineers understood it well. The common examples were 3A5s, 810s or maybe 813s in push pull pairs (both have directly heated cathodes). Allison

20 years, 7 months

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A BDU's is born every minute ...

by pete＠dunnington.plus.com

On Oct 18 2005, 8:29, John Foust wrote: > At 01:39 PM 10/17/2005, Bob Bradlee wrote: > >With the aid of a paperclip and a prybar, I opened up the drive to fine a > >shattered CD inside. > But I've seen this happen *twice* to a client who wasn't > dunking them in LOX. CDs are spinning quite quickly. I've never actually seen it happen, but a couple of years ago one of the manufacturers who supplies the University issued a warning about fast drives, and IIRC some were recalled. The explanation was that the faster "52x" drives run at a speed which is very close to that at which centrifugal force can make a polycarbonate disk break up, so a defect in the disk can have a profound effect. -- Pete Peter Turnbull Network Manager University of York

20 years, 7 months

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PC floppy cable twists...

by Richard.Cini＠wachovia.com

Regarding the drive termination, I distinctly remember pulling terminators on the middle drive in a two-drive setup...just like a SCSI chain. I don't know about new drives (because I don't usually have multiple drives in my machines now), but some more modern Teac drives have a termination jumper rather than a resistor DIP pack. -----Original Message----- From: cctalk-bounces at classiccmp.org [mailto:cctalk-bounces at classiccmp.org] On Behalf Of Chuck Guzis Sent: Thursday, October 20, 2005 1:19 PM To: cctalk at classiccmp.org Subject: Re: PC floppy cable twists... On 10/20/2005 at 5:48 PM Jules Richardson wrote: >... discussion about this on another list got me curious - what *was* >the point of that cable twist in a (IBM clone) PC floppy cable, when >every other system on the planet was using straight-through cables? It's actually pretty simple--there's only a single "motor on" line for the standard floppy pinout. IBM wanted to control drive motors individually. The only ways to do that are with individual drive cables or using the "twist" (or some modification of it) so that the individual drive motor enables are given different conductors in the cable. Other systems using "straight through" cables switched all drive motors on and off--and many consequently used drives with head-load solenoids. IBM's solution let them economize a bit on power-supply design and use a cheaper (and quieter) drive without the head-load mechanism. FWIW, IBM makes no mention of terminator removal or addition and I don't even recall if the standard 5.25" drive allowed one to play with termination. On one of the ISA floppy/hard controllers--I think it was DTC--you could add a third drive to the string using a special cable and a drive jumpered for DS0. (I'd have to check my doc files to get the rest of the details on the cable construction). Cheers, Chuck

20 years, 7 months

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Snoopy calendars/ASCII art

by rcini＠optonline.net

All: There's a listing on eBay for ASCII art TTY printouts (#8707360741) and it raised an interesting question. I remember as a kid going to my father's office (he worked for New York Telephone in New York City) at Christmas and they had various computer systems that they let the kids play on. One of them (I don't remember which) had a program to print calendars. In the eBay listing, there's a Snoopy Red Barron calendar, which I distinctly remember printing out. What program would have made this calendar and is one still available, somewhere, that I could run on Windows or through something like SIMH? Rich Rich Cini Collector of classic computers Build Master for the Altair32 Emulation Project Web site: http://highgate.comm.sfu.ca/~rcini/classiccmp/ /************************************************************/

20 years, 7 months

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computer speedometer

by charlesmorris＠direcway.com

>I was reminiscing to someone about an old GE mainframe > with an analog meter that registered Kops/sec. ... made by Keystone Electronics perhaps? :) -Charles

20 years, 7 months

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Bell and Howell "Digital Video Presentation" system

by SUPRDAVE＠aol.com

>In a message dated 10/19/2005 6:56:33 PM Eastern Daylight Time, >julesrichardsonuk at yahoo.co.uk writes: >We've just been offered one of these - I'm assuming (awaiting further >details) that it's a rebadged Apple II Plus, as in: >http://oldcomputers.net/bellandhowell.html >... but that doesn't mention the "Digital Video Presentation" side of >it, or even any video extras over and above what the II Plus has. >Anyone know any more details? Did Bell and Howell ever do any other >computer-based systems? >I will get some more info from the owner (and they have the full doc set >apparently), but I'm being impatient :-) That's interesting, I work at B+H (now Bowe Bell and Howell) and I've never heard of any of the old stuff at work. BBH is primarily know for mail processing systems and technologies, neat stuff!

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OT: Tube Audio

by leeedavison＠yahoo.co.uk

> I didn't say nonexistant, only rare. Dynaco was amoung the best > then. The alternate was a filiment that was balanced to ground to > minimize the amplitude of AC heater to cathode coupling, also only > seen on quality gear. Another, rarer, alternate used with directly heated cathodes is to have two cathodes heated by a Scott wound transformer that gives two phase AC current with a 90 degree phase difference. This reduced heater generated noise because the noise is a function of the square of the heater voltage and sin^2 + cos^2 = 1, effectively a DC component. I have only ever seen this arrangement used on broadcast equipment. Lee. . ___________________________________________________________ To help you stay safe and secure online, we've developed the all new Yahoo! Security Centre. http://uk.security.yahoo.com

20 years, 7 months

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Filters for RL02

by charlesmorris＠direcway.com

Gordon recently mentioned that he had a dwindling supply of absolute filters for his RL02 drive. They are still readily available from several sources including Air Filtration Products (airfiltrationprod.com) and isesurplus.com. I just ordered one from The Filter Factory (www.thefilterfactory.com) for $28.95 plus UPS. -Charles

20 years, 7 months

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test-drb October 2005