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101090 discussions

Is DECtape Read/Write Head "In-the-Weeds" Info Available?

by bobvines00＠gmail.com

Does anyone have "in-the-weeds" information on the DECtape read/write heads? I've got several TU-55 transports and a box of DECtapes (thank you very much Doug!) _and_ Michael's failed DECtape head from several years ago that I'm de-potting. I very much want to figure out how to repair Michael's DECTape head and will return it to him if I can do so. I've read the document that Al posted a link to in the discussion on DF32s: Message-ID: <1e97981e-05d9-f272-d2fe-10ae38da6668 at bitsavers.org> ... "remided me of the problems with rhodium plating on RF08 drives here on page 9 http://archive.computerhistory.org/resources/access/text/2012/08/102746014-… " The "Oral History of Grant Saviers" is interesting and gives a lot of information about various storage technologies that were used over the years. It reminded me of my desire to learn everything I can about DECtape _and_ DECtape transports. Maybe the CHM or someone else has interviews or tech data that helps answer my request? Bob

4 years, 8 months

Need to have a roll of paper punch tape read by a tape reader and printed

by camiel.vanderhoeven＠vmssoftware.com

Gary, I don't know if you're in Europe or elsewhere. I'm in the Netherlands, and I could do that free of charge. I'd also make a video recording of the process for your sons education. Camiel ________________________________ From: cctech <cctech-bounces at classiccmp.org> on behalf of Gary Dye via cctech <cctech at classiccmp.org> Sent: Monday, March 8, 2021 11:30 PM To: cctalk at classiccmp.org <cctalk at classiccmp.org> Subject: Need to have a roll of paper punch tape read by a tape reader and printed Hi folks. I wrote a basketball program in Basic over 40 years ago in high school. I printed the 13 pages of code, and produced a roll of paper punch tape of the code, but the 13 pages were destroyed, leaving me with only the paper tape. My 14-year-old son was pretty fascinated to see the roll of computer punch tape -- paper with holes in it! -- that we used to store files in the old days. And that we didn't have computer screens, but only a teletype element that printed -- one letter at a time -- the back-and-forth information between the timeshare computer and the teletype (output). This paper punch tape is the Basic program that I wrote in high school that played a random basketball game (as called by Bill Schonely, radio voice of the Portland Trailblazers). I'm trying to find someone to run it through a tape reader so that I can retrieve the code and play the game again. I'm hoping to explain the code to Owen so that he might understand the power of coding and get interested in coding. Is there anyone out there that I can send my roll of paper tape to such that the code can be restored? I could pay some compensation for your troubles. Much appreciated, Gary This e-mail (including any attachments) may contain privileged, confidential, proprietary, private, copyrighted, or other legally protected information. The information is intended to be for the use of the individual or entity designated above. If you are not the intended recipient (even if the e-mail address above is yours), please notify us by return e-mail immediately, and delete the message and any attachments. Any disclosure, reproduction, distribution or other use of this message or any attachments by an individual or entity other than the intended recipient is prohibited.

4 years, 8 months

DF32?

by cz＠alembic.crystel.com

There's a DF32 on Ebay. I've got a bid in on it, will see what happens. In the unlikely event I win I'll have to build a system to adapt the Negibus to the pdp8/L. However did the pdp8/L have 3 cycle data break? C

4 years, 8 months

Need to have a roll of paper punch tape read by a tape reader and printed

by marvin＠west.net

OOPS on my last response... I should have said I found the original on the CCTECH archive. Hope there was no confusion there!

4 years, 8 months

Need to have a roll of paper punch tape read by a tape reader and printed

by marvin＠west.net

FWIW, I went back to the CCTALK archives and could not find the original message either. Being curious, I went back to the CCTALK archives and there it was. > Hi folks. I wrote a basketball program in Basic over 40 years ago in high school. I printed the 13 pages of code, and produced a roll of paper punch tape of the code, but the 13 pages were destroyed, leaving me with only the paper tape. My 14-year-old son was pretty fascinated to see the roll of computer punch tape -- paper with holes in it! -- that we used to store files in the old days. And that we didn't have computer screens, but only a teletype element that printed -- one letter at a time -- the back-and-forth information between the timeshare computer and the teletype (output). This paper punch tape is the Basic program that I wrote in high school that played a random basketball game (as called by Bill Schonely, radio voice of the Portland Trailblazers). I'm trying to find someone to run it through a tape reader so that I can retrieve the code and play the game again. I'm hoping to explain the code to Owen so that he might understand the power of coding and get interested in coding. > > Is there anyone out there that I can send my roll of paper tape to such that the code can be restored? I could pay some compensation for your troubles. > > Much appreciated, > > Gary

4 years, 8 months

Tymshare PDP-10 tapes

by lars＠nocrew.org

Hello, Someone sent me these magtape images from Tymshare and said "they fell off the back of a truck on route 62 in Hudson, MASS." I don't know their provenance. Sorry, I don't have any good hosting. For now they are here: https://gitlab.com/larsbrinkhoff/tymshare The download.sh script will retrieve individual files one by one rather than cloning the repository; next use cat.sh to get the .tape.bz2 files. The tape format is close to not not quite FAILSAFE. With help from Joe Smith, I made a tool to extract the files: https://github.com/larsbrinkhoff/pdp10-its-disassembler/blob/master/tito.c

4 years, 8 months

From SIMH list: Whirlwind software recovery

by phil＠ultimate.com

> From: "Christian Brunschen" <christian at brunschen.com> > Date: Mon, 8 Mar 2021 21:45:11 +0000 > Subject: Re: [simh] recovering software for the MIT Whirlwind > To: simh at groups.io > > https://www.historia-mollimercium.com/whirlwind/ww-page.html > https://www.historia-mollimercium.com/whirlwind/Whirlwind-Software-Recovery… > ? > > On Mon, 8 Mar 2021 at 21:41, "Nelson H. F. Beebe" <beebe at math.utah.edu> > wrote: > > > The latest issue of IEEE Annals of the History of Computing has an > > article that may be of interest to some list members: > > > > G. C. Fedorkow > > Recovering Software for the Whirlwind Computer > > IEEE Annals of the History of Computing 43(1) Jan/Mar 2021 pp. > > 38--59 > > https://doi.org/10.1109/MAHC.2020.3048815

4 years, 8 months

Spelunking the places where files are not

by jfoust＠threedee.com

At 03:16 AM 3/8/2021, Tor Arntsen via cctalk wrote: >Linux distros come with a standard tool to do some of that, >'testdisk'. From the overview: I'm familiar with the various undelete tools for Windows and Linux. Such tools may not exist or make sense for older file systems. Entire files would be great to find, but I suspect interesting fragments may be more likely. Running a Windows-based tool like Recuva on a hard drive leads to such a firehose of fragments if you choose the deep scan that examines all unused blocks. I've only tried the free version. Does the pro version give you a way to exclude all the dozens of OS file types that are probably not the user-made files that you want? And for the archaic disk formats, it would be good to have platform-specific methods of identifying fragments to guess their file type beyond executable and ASCII. Older run-length compression image formats may be more possible to recover than today's block-compressed images. - John

4 years, 8 months

RSTS processor identification

by paulkoning＠comcast.net

I was just asked some questions about how RSTS identifies your processor type. Since that topic might be of broader interest I figured I'd do some code reading and summarize the logic. In the RSTS initialization code (INIT.SYS), the first step is to identify what your hardware looks like. That is a combination of CPU type, bus type, memory layout, and peripheral configuration lookup. They aren't strictly separated into sequential blocks for those four activities, though naturally you'd want to know the bus type before you start looking for I/O devices on that bus. What I describe here is in RSTS/E V10.1. The general idea of scanning the hardware was introduced in V6B, and I believe is basically the same from that time onward apart from the addition of support for more hardware types. Prior to V6B, the assumption was that you had the hardware you specified during SYSGEN, neither more nor less. Here is an outline (not all the details) of the hardware scan flow: 1. If word 0 of the boot block contains a zero, this is a Pro (CT bus); otherwise it isn't. 2. Make sure the MMU exist; if not, halt. 3. Check the CPU type (MFPT instruction). If it's an F-11, see if 177570 exist. If yes, 11/24 (Unibus); if no, 11/23 (Qbus). If it's a J-11, read the board type register at 177750 and use the bus type bit to distinguish Qbus from Unibus. 4. Check that there is a clock, and if possible determine the power line frequency. 5. Check if there is a CPU cache, and whether there is a cache error address register. 6. If Qbus, check whether there is memory above the 18 bit range. 7. Check that there is at least 96kW of memory (but the message says that 124kW is required -- the actual check value was apparently overlooked and not updated). 8. Check CPU features: EIS (required), FPP, FIS, switch register, display register, MED, two register sets, system ID register, CIS, Data space. 9. If Unibus, check for UMR. 10. Find where memory is. This is done by looking at every 1kW address to see if it answers. So unlike some other operating systems, RSTS will keep looking if it finds a hole in memory. The kernel needs to be at 0 and contiguous, but holes above that are not a problem. 11. Scan the I/O bus for peripherals. This uses the fixed addresses and float rules for Unibus/Qbus (either, the code doesn't care) or the slot use bits and device type register codes for the Pro. 12. Find the vectors, which for almost every device is done by making it interrupt. 13. Identify specific device models if we care, like RL01 vs. RL02, Massbus disk type, DMC/DMR/DMP, etc. 14. Find which of these devices we were booted from. That's about it. Once you get past that point the INIT prompt appears and you can ask what INIT found with "HARDWARE LIST". Incidentally, RSTS doesn't try to identify the exact CPU type you have. Instead, it cares about features or distinctions that affect the code. In a number of cases it does report the type -- if MFPT works then "hardware list" will report that information. But for older CPUs, it doesn't say explicitly, though you can deduce it to some extent. If no type is given but there is cache and more than 128 kW of memory, it's an 11/70. If MED is available, it's an 11/60. If it has FIS, it can only be an 11/40. Etc... paul

4 years, 8 months

RSX11D disks on EBAY- anyone interested?

by lee.gleason＠comcast.net

? Saw this on EBAY today - three RK05s with what looks like at least part of RSX11D on them. Who knows, it might be a distribution - RSX11D distributions came on 3 RK05s. https://www.ebay.com/itm/PDP-11-RSX-11D-Executive-Programs-Phase-II-3xRK05-… ? The auction starts at? more than I have in my computer budget this month, though - would some other RSX historians like to go in together on this (preferably at least one person with an RK05 drive)? ? I'd just like the contents of the disks - I don't care about the physical disks, just what's on 'em -- Lee K. Gleason N5ZMR Control-G Consultants lee.gleason at comcast.net

4 years, 8 months

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