test-drb October 2005

test-drb@ccmp.vtda.org

264 participants
655 discussions

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

18 years, 9 months

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

18 years, 9 months

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

18 years, 9 months

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

18 years, 9 months

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 >>

18 years, 9 months

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

18 years, 9 months

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

18 years, 9 months

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

18 years, 9 months

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. > > > >

18 years, 9 months

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

18 years, 9 months

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test-drb October 2005