test-drb January 2015

test-drb@ccmp.vtda.org

175 participants
253 discussions

by spereira1952＠comcast.net

Hello from a lurker here, I am looking for a pointer to where I might be able to obtain the assembly / reference / user manual for the IMSAI PCS-80/15. Printed form or electronic copy, either way will be fine with me. Thanks very much, in advance, for your attention, and, hopefully, positive response! smp - - - Stephen Pereira Bedford, NH 03110 KB1SXE

10 years, 3 months

Maxtor XT-2190

by djg＠pdp8online.com

Someone was using my MFM reader to read a Maxtor XT-2190 and was having problems. From the looks of it the heads are out of alignment. Does anyone know if this drive has a microstep mode like some Seagates have? I didn't find any mention in the manuals I could find. Some heads are mostly unreadable, some heads are mostly ok and some were unreadable on cylinder 0 and on other cylinders the header says they are one cylinder less than where it stepped to. Some of the other heads headers said the cylinder is what was expected.

10 years, 3 months

MEM11 Status Update

by jnc＠mercury.lcs.mit.edu

> From: Guy Sotomayor > a multi-function Unibus board that contains all of the more difficult > items to allow a PDP-11/20 to run Unix V1 entirely within the CPU > chassis. Other than the CPU and the RK11-D controller, everything else > will be on the MEM11 board. > ... > What's on the board is the following: > ... > RF11 controller with non-volatile memory emulating 8 RS11 drives What form is the NVM in - an SD card, or just a chip, or what? I assume it's flash memory of some kind? (What's the limit on the number of write cycles with current flash memory, I wonder...) BTW, a removable card would be great - that would provide a way to get bits into the machine, other than loading them all in over a serial line. I'm kind of curious about your decision to only have an RF11, given the capacity of contemporary flash memory chips/cards. Why not an RK11 too? (You may have plenty of RK controllers/drives, but some of the rest of us aren't so lucky... :-) Is there not enough room in the 16K code block to do that too? And how about an RP11 too, for those of us running these cards in later PDP-11's? :-) (Oh, speaking of the 16K limit - any way to increase the size? Probably not without munging the J1 architecture, I would guess - I need to go grab it and read it. But limited addresses spaces always turn out to bit you where it hurts... :-) > As I was competing the configuration UI, I found that I couldn't have > both the configuration UI and the emulation code both fit in 16K > (strings take up a lot of space). I seem to recall this problem from my days of writing packet switches for PDP-11's... :-) The code was famous for log messages that left out all the vowels, to save space.. :-) Please, make the UI as cryptic as needed to make all the features (e.g. more disk controllers :-) fit - documentation can explain what all the cryptic names are. (Or perhaps even a front-end running on a PC which is connected to the MEM11 over the serial line.) Don't take any of this to mean I don't think this is really, really neat, and very impressive - it's both! Needless (perhaps) to say, I'll be buying a stack of these when they are ready! :-) Noel

10 years, 3 months

Operating systems of the 1970s handling dates beyond the year 2000

by cubexyz＠gmail.com

After trying to get Unix v5 to understand dates beyond the year 2000 I had to wonder if any of the older operating systems from the 1970s or older could do this. So, did any operating system programmers from this time period have the foresight to use 4 digits for the year? I just checked APL/360 and it seems that it does not. Mark L

10 years, 3 months

MEM11 Status Update

by jnc＠mercury.lcs.mit.edu

> From: Jay West > My hope is to drop one of these boards in my 11/45. The only issue is > I'm afraid even though it will give the /45 maximum memory Well, there is that board (by Able?) that allowed a /45 to have up to 2MB of main memory. I know they exist[ed], we had one on our 11/45 at MIT 'BITD'. It didn't require any mods, it was a simple plugin - although my memory doesn't recall how the bus from the board to the memory worked, whether it used an over-the-back connector, or if the expansion board, and memory, plugged into a custom backplane (I have this vague memory that it could use Extended UNIBUS memory, a la 11/44, so maybe it was a custom backplane). I do recall that it had a whole separate set of mapping registers, to map the entire 'outbound' (from the CPU) UNIBUS to the larger memory, and also a UNIBUS map for the 'inbound' UNIBUS (from the devices) to map into the memory - i.e., it did not have access to the CPU mode/space signals, so it didn't have K/S/I PARs. One had to set up the mapping registers in the 11 as well. We used a static mapping where User I and D went to fixed chunks of address space in the 'outbound' UNIBUS, and the expansion MMU then mapped those chunks (variably) into the larger main memory. IIRC, we just changed the definition of the address of the User PAR registers (but kept the User PDRs), and the UNIBUS map registers (although maybe those were at the same locations as those in the 11/70), and then re-compiled the affected kernel modules. (The assembler startup required a bunch of changes, too.) I should have all that code on my backup tapes... That might not have supported I+D for K, S and I (since together they need 128KB*3 bytes, more than a complete UNIBUS address space), but it worked OK for the early Unix we were running. > I think I have too many pdp11 racks and it could be time to thin the > herd before too long. Or maybe I just need to get more space. Yah, > that's the ticket! Please put me on the list for an -11 stuff you get rid of... ;-) Noel

10 years, 3 months

Data Products 2230 manual?

by hachti＠hachti.de

Hi folks, my Data Products 2230 drum printer recently stopped working. The trouble began a few years ago: Startup went wrong from time to time so that the printer control logic was stuck after power on. Repowering helped. But now it does not help anymore. I found the DP2230 service manual 2 on bitsavers. It contains the machine's schematics. That already helped me to trace the problem - a bit. It looks like the buffer/interface logic does mad stuff. At this point it gets quite difficult to understand the logic without any explanation. Does anyone have the service manual part ONE? I assume that this contains info about state machines, test points and procedures, explanations etc. A (probably pdf) copy of that manual would help me a lot. I would very much appreciate to get hold of it. Kind regards Philipp :-)

10 years, 3 months

Shipping antique computers

by marc.verdiell＠gmail.com

Thank you Todd. Very useful info. Marc >From: Todd Goodman <tsg at bonedaddy.net> >Subject: Re: Shipping antique computers >Message-ID: <20150118203355.GG4901 at ns1.bonedaddy.net> >I've palletized and shipped computer stuff as well as pinball machines >as well as received both on pallets. >[...] >Just my experience with it. >Todd

10 years, 3 months

IBM Mainframe/Peripherals on eBay...

by lbickley＠bickleywest.com

There's what looks to be a nice collection of IBM Mainframe goodies on eBay: http://www.ebay.com/itm/Vintage-IBM-Computer-Mainframe-Lot-with-2-printers-… or Item #161566683205 Local Pickup, Huntington, New York NOT my listing - just "stumbled" across it today Cheers, Lyle -- Bickley Consulting West Inc. http://bickleywest.com "Black holes are where God is dividing by zero"

10 years, 3 months

Operating systems of the 1970s handling dates beyond the year 2000

by cctalk＠beyondthepale.ie

> >> After trying to get Unix v5 to understand dates beyond the year 2000 I >> had to wonder if any of the older operating systems from the 1970s or >> older could do this. >> >> So, did any operating system programmers from this time period have >> the foresight to use 4 digits for the year? I just checked APL/360 and >> it seems that it does not. >> > > TOPS-20? VMS? > It was very near the end of the 1970s but VMS made a really good effort to handle times and dates well from the beginning. A single 64 bit time format is used throughout the operating system and operating system routines are provided to manipulate it and convert to and from well chosen standardised display formats with no ambiguities such as two digit years or easily mixed up numbers for days and months. Everything [*] displays and accepts the same time and date formats and shortcuts such as YESTERDAY, TODAY and TOMORROW. No messing about trying to figure out what format a particular utility wants the date specified in and no wondering whether a unitless time displayed by something is days, hours or minutes. The areas where I think it could have been done better still are to have stored the time internally in UTC rather than local time while displaying local time and to have chosen an earlier base date than 17 November 1858. Also, there was originally a rule that time differences could not be larger than 10000 days which was poorly enforced and eventually had to be scrapped - this should have been handled much more gracefully. [*] A few system parameters are specified in seconds and TIMEPROMPTWAIT is specified in microfortnights with tongue in cheek. Regards, Peter Coghlan.

10 years, 3 months

Operating systems of the 1970s handling dates beyond the year 2000

by johnwallace4＠yahoo.co.uk

"an *awesome* cover letter that DEC sent out with the fix, assuring everyone that the libraries were now good internally until some crazy year like 31078, but there was still formatting code that assumed years fit in four digits so there would be Y10K bugs; but don't worry, DEC will issue a patch to VMS at that time." Sounds a little bit like (but maybe not identical with?) the well known Stan Rabinowicz Leap Year Software Performance Report (SPR) response in 1983 for VMS V3.2? Stashed in various places which search engines should find, currently including HP's website and http://www-users.cs.york.ac.uk/susan/joke/decly.htm Have a lot of fun John

10 years, 3 months

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test-drb January 2015