test-drb May 2020

test-drb@ccmp.vtda.org

163 participants
133 discussions

by jfoust＠threedee.com

At 09:25 AM 5/28/2020, Bill Gunshannon via cctalk wrote: >Nothing like asking people to jump thru hoops before you let them >do you a favor. :-) Much of the effort of running a thrift store is disposal of donated material that has no rapid resale value. - John

4 years, 4 months

Back to tech: TK50 restoration and thoughts

by cz＠alembic.crystel.com

Ok, so to get back to technology I have been working on fixing the TK50's I have here along with attempting to look at some old tapes from Bob's basement. It's been interesting. So far one of the units works well with one of my tapes (stored indoors for about 20 or so years) after a good cleaning with 95% isopropyl alcohol. From RT11 I was able to initialize the tape, write 40mb of .DSK image files, and consistently read the files back (to a VM: memory drive) and diff/bin them to make sure they are the same. Good. First test: A second TK50 drive I had banging around. This one will read the tape, but fail about half way through. May still be a bit dirty, will clean and check. Second test: Checking some of the tapes from Bob's basement. In addition to getting the PERQ tapes out of there I had a few TK50 tapes mixed in, most with degaussed stickers on them from long ago. These tapes appear to have been Vax 8650 load tapes of some sort, no idea if there is any value to the data but one was labelled Micro-pdp11 diagnostics and since I know those are backed up I started with that one. It loads, but fails with a DUP IO output error. It also messes up the tape head so I have to clean it after testing. Most of the dirt is at the bottom of the head. After cleaning the drive can load and read the "control" tape which has all of those image files on it, so it doesn't damage the drive. Still I see why taking the cage top off the TK50 is a good idea. :-) Took the cartridge apart and here is what I see: https://i.imgur.com/xHhiBAW.jpg This is... not good. Dirt or something on the bottom of the tape. Now these did spend the last 20 years in a pretty dank basement with an oil fired house heater so there is probably that. Still I used a Q tip on the tape with isopropyl alcohol and it came up dirty inside the cart and out: https://i.imgur.com/TB91gGx.jpg Also odd that the tape is wrapped in two different "levels" on the spindle. Maybe that's normal. So a question: Can one clean tape with isopropyl alcohol? In theory if I could get the controller to slowly run the tape onto the take-up real to the EOT marker I could soak some cotton swabs and use them to clean the tape before it hits the heads (to minimize head wear). Or I could just chuck these tapes and see how a couple I am buying from Ebay hold up. This is mostly an academic exercise: It gives me something to do. But I am wondering if the tapes were crudded by the environment or if this is just natural tape degradation. I do have one final tape that was in a closed tape holder so it might be better (it's clean on the outside). Will see.... C

4 years, 4 months

Replacing cables sheaths?

by matti.nummi＠hotmail.fi

You can use cable lacing. It does not make it pretty(er), but usable. If You don't want to remove the connectors or cut the cable You cannot add any new sheath? There may be some fabric/wowen expandable sheaths which have been used on power cables earlier but I have no precise knowledge. Something like when You push it, it bulges. BR Matti

4 years, 4 months

Living Computers: Museum + Labs

by RichA＠livingcomputers.org

Hello, everyone, As I'm sure all of you are aware, the COVID-19 pandemic has led to a crisis with devastating effects on many cultural organizations, and more especially on those which rely on public gatherings and special events to achieve their mission. Since before we opened to the public in 2012, our philosophy has been a simple one: To understand computing technology of any period, you need to experience that technology at first hand. The current global situation has made it difficult for us to serve our mission, and given so much uncertainty we have made the difficult decision to suspend all operations of LCM+L for now. We will spend the months ahead reassessing if, how, and when to reopen. Because that will not happen in any short time frame, the staff, including me, have been laid off. On a personal note, the last 17 years, since July 2003, have been a time of growth, excitement, and backbreaking labor which I would not trade for anything. The friendships I have formed, in the community at large (and it is international in scope) as well as among my colleagues here, are a comfort to me. I'll be subscribed from a personal address once that is moderator-approved. Thank you all for your interest in and support for Living Computers: Museum + Labs, and our previous incarnations. It means a great deal to us as we wind down the current implementation. Rich Rich Alderson Sr. Systems Engineer/Curator emeritus Living Computers: Museum + Labs 2245 1st Ave S Seattle, WA 98134 Cell: (206) 465-2916 Desk: (206) 342-2239 http://www.LivingComputers.org/

4 years, 4 months

In search of Apollo DN100 Technical Reference Manual

by ian.finder＠gmail.com

Hi folks, I've recently acquired an Apollo DN100 I'd like to restore to former glory. Sadly, there are no schematics anywhere that I can find. I have seen this alluded to, but do not have a part number- anyone got a lead? Even better would be to find anything describing the PALs in the system. Separately, there is a 14" Priam DISKOS hard drive in here- not with the Priam interface used by the later SAU2 Apollos (DN300, etc.) but something else- perhaps the early ANSI interface option provided by Priam. If anyone has leads on - 1) The failure modes of these drives and 2) A replacement ? advice would be much appreciated. Thanks, - Ian

4 years, 4 months

In search of SGI IRIS 1400 / 2000 era technical reference manuals & schematics

by ian.finder＠gmail.com

Title says all. Thanks, - Ian

4 years, 4 months

Replacing cables sheaths?

by cruff＠ruffspot.net

Does anyone know of an effective technique to replace the sheath of a cable without needing to reterminate the ends? On all of the Apple power adapter cables I've used the plastic sheath starts to fall apart, but the adapter itself and the cable conductors are still useable. Something that results in a reasonably flexible coating that doesn't look like a horrible accident happened to the cable? :-)

4 years, 4 months

Last MSV11-P question: Using them as Q bus memories

by cz＠alembic.crystel.com

Ok, so we banged the MSV11-P revision B/C memory issues into the ground (looks like the problem is burst mode DMA on Q Bus can cause random failures that corrupt disks) however does anyone know if the bug will affect the board if you use it as a normal Q bus memory board? In other words, if you put the board *below* an 11/73 or 11/83 so it reports as a non-PMI memory will it still have the same problem? I'd like to run my system with a full 4mb of memory, using my normal parity 2mb board and a 2mb MSV11-P board that was from an 11/83? Inquiring minds want to know :-) C

4 years, 4 months

Algol W [was: Microsoft open sources GWBASIC]

by paul＠mcjones.org

> On May 26, 2020, Al Kossow <aek at bitsavers.org> wrote: > > On 5/26/20 6:39 PM, Al Kossow via cctalk wrote: >> >> >>> Algol W was from Eroupe? >> >> Algol W was from Stanford, written by Wirth when he was there > > Actually, by Dick Sites > > http://bitsavers.org/pdf/stanford/cs_techReports/STAN-CS-71-230_Algol_W_Ref… <http://bitsavers.org/pdf/stanford/cs_techReports/STAN-CS-71-230_Algol_W_Ref…> Dick must have done a lot of work on that version, but an earlier manual by Henry R. Bauer, Sheldon Becker, and Susan L . Graham says: The project was initiated and directed by Professor Niklaus Wirth, who proposed many of the ideas incorporated in the compiler and suggested ways to bring them about. Joseph W. Wells, Jr. and Edwin H. Satterthwaite, Jr. wrote the PL/360 System in which the compiler is embedded, the linkages to the compiler, and the loader. Although the authors did the bulk of the programming for the compiler, valuable contributions were made by Larry L, Bumgarner, Jean-Paul Rossiensky, Joyce B. Keckler, Patricia V. Koenig, John Perine, and Elizabeth Fong. http://i.stanford.edu/pub/cstr/reports/cs/tr/68/98/CS-TR-68-98.pdf And Ed Satthertwaite wrote a source-level debugger for the system. More on Algol W here: http://www.softwarepreservation.org/projects/ALGOL/algol60impl/#ALGOL_W and more on the designs that led up to it here (search for the names Wirth and Hoare): http://www.softwarepreservation.org/projects/ALGOL/standards/ in particular: N. Wirth and C. A. R. Hoare. A contribution to the development of ALGOL. Communications of the ACM, Volume 9, Number 6 (June 1966), pages 413-432. ACM Digital Library <https://doi.org/10.1145/365696.365702> "Euler caught the attention of the IFIP Working Group that was engaged in planning the future of ALGOL. The language ALGOL 60, designed by and for numerical mathematicians, had a systematic structure and a concise definition that were appreciated by mathematically trained people but lacked compilers and support by industry. To gain acceptance, its range of application had to be widened. The Working Group assumed the task of proposing a successor and soon split into two camps. On one side were the ambitious who wanted to erect another milestone in language design, and, on the other, those who felt that time was pressing and that an adequately extended ALGOL 60 would be a productive endeavor. I belonged to this second party and submitted a proposal that lost the election. Thereafter, the proposal was improved with contributions from Tony Hoare (a member of the same group) and implemented on Stanford University's first IBM 360. The language later became known as ALGOL W and was used in several universities for teaching purposes." [Wirth 1985 <http://www.softwarepreservation.org/projects/ALGOL/standards/history/#Wirth…>]

4 years, 4 months

history is hard

by sieler＠allegro.com

Fred writes: ..."MS-DOS 3.3 did not even come with a disk cache." and discusses problems with SMARTDRV (in MS DOS 4.01 and later). I'm not sure if it was technically a form of caching, but the AmigaDOS delayed floppy write (well before MS-DOS cache) caused enormous problems for Amiga users. (It may well have contributed significantly to the lack of market success.) Basic problem: you save something to a floppy, and pull it out. You now have a corrupted floppy. You needed to wait a few seconds for the OS to decide "well, looks like I better flush the last few dirty sectors out to that floppy". (I contend it was a form of write caching, designed to speed writing to floppies where writing tended to occur in nearby places.) Stan

4 years, 4 months

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test-drb May 2020