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101090 discussions

Overland T490 cartridge tape drive and autoloader

by cctalk＠beyondthepale.ie

Many years ago, a friend gave me an Overland T490 tape drive which has some kind of autoloader attached which takes ten tapes. I was told it came out of a Tandem system. The tapes are square cartridges similar but different to a DEC TK50. I can't find very much information about the drive on the web but there are some hints that it might be compatible with an IBM 3480. It powers up nicely and the fan works and after a short pause, a green LED illuminates. There are only two buttons on the front, "unload" and "format". There are two DD50 connectors on the back. One had a terminator plugged into it labelled "SCSI differential". The other had a ridiculously long cable with DD50 plugs on it connected, lending further credence that this is a differential (pre-LVD I expect) SCSI device. I would like to get this drive working with my Alpha or VAX VMS systems but I have never had any luck getting them to talk to it. Recently, I tried a using a DD50-HD68 cable I found somewhere to connect it to a differential SCSI card in my Alphaserver 800 but I could not get VMS to see the drive. Not knowing what SCSI id the drive is likely to be using makes it hard to know where to start looking for it. There are no switches on the outside of the drive which could be used to set the SCSI id so I opened it up to see if I could find any hints inside. I didn't see anything that looked like it could be used to set the SCSI id inside either. What I did find is that the interface board had a connector labelled "SCSI differential" which had two short lengths of ribbon cables plugged into it leading to the two DD50 connectors on the rear panel and another connector labelled "SCSI single ended" with nothing attached. There were also two ten way jumper packs which were labelled "DI" and "SE" on each side. So, not having any luck with differential so far, I tried moving the two jumper packs from "DI" to "SE" and moving the ribbon cable to the "SCSI single ended" socket. I used a short, known good DD50-DD50 SCSI cable to connect the drive to my VAX 4000-100A and replaced the differential terminator with a known good single-ended terminator. VMS didn't see the drive. VMS has a utility called scsi_info which can be used to send a SCSI inquiry command and read mode pages etc. Trying it against each unused SCSI id results in "device timeout" every time. The system disk is on the same SCSI bus before the tape drive and a SCSI scanner can be connected after it on the bus. Both devices work fine so the SCSI bus cabling and termination is in good shape on both sides of the tape drive. I've tried moving the system disk SCSI id from 0 to 1, changing the initiator SCSI id from 6 to 7 and replacing the scanner with a terminator in case there is any sort of SCSI id conflict but scsi_info still doesn't show up anything that could be the tape drive. Does anyone have any information about this drive, particularly whether it should behave like a standard SCSI tape drive and what SCSI id and/or lun it is expected to use or if there is some trick required to get it to start talking? Maybe it doesn't like SCSI inquiry commands? Extra bonus points awarded for details on how to control the autoloader. Maybe I did some damage to it when I was trying to get it to work when I first got it? Regards, Peter Coghlan.

4 years, 1 month

Reproduction DEC 144-lamp indicator panels

by jnc＠mercury.lcs.mit.edu

> From: Jay Jaeger > Also, if someone (else, presumably) does up a replica of the indicator > panel board (perhaps with the option to use LEDs, with some resistor > packs that could be bypassed for lamps Two points. First,there's the question 'are you trying to produce something that just _looks_ alike, or do you want something that's electrically compatible (i.e. can be swapped in in place of an original'? If the latter, it might be going to take a little work; it might not be just 'wire up some LEDs and go'. If you look at the indicator panel prints (pg. 190 of the RF11 prints), the incoming lines are tied to the base of a transistor; its emitter is tied to ground, and the light bulb is wired between the collector and +6.5V. This means, I think (I'm basicaly a software guy :-), that one turns the bulb on by putting a voltage on the input, which turns the transistor on, and current flows through the bulb to ground. (If I have that wrong, will someone please orrect me?) Given that the way TTL works is that 'logic' outputs actually sink currect when their output is '0' (i.e. current goes _in_ the 'output' pin), it might take a little work to make the right thing happen. Although maybe not; looking at the RK11-C prints, it seem to drive the indicator panel straight >from the output of normal gates. I _think_ what happens is that when a gate's output is '1', the output's voltage floats high, and that's enough to turn on the transistor (above) driving the bulb. (Ditto the request for correction!) But the real issue with 'electrically compatible indicator panels' is the wiring. In the originals, the flat cables that drive them are soldered directly to the indicator panel board, and also to the paddle boards. So the _only_ standard interface location is the paddle boards. I suppose one could put Berg headers on both the indicator panel board and the paddle boards, and use a standard IDC cable betweenthe two... Mention of the paddle board interface brings me to the second point: even if one did produce electrically-compatible indicator panels - where are you going to use them in a PDP-11 system? Not in the CPUs - those all had their own front panels. The only PDP-11 devices which used indicator panels which I know of were: - the DX11 (I don't think anyone's got one of those) - the RF11 (ditto - although Guy was discussing emulating one at one point) - the RP11 (but the indicator panel is built into the controller rack there, so if one has an RP11, one already has the indicator panel) - the RK11-C (and several people who have those already have indicator panels) I agree, the indicator panels look cool - but where are you going to use one in a historical PDP-11 system? Sure, one could use either a electrically-compatible or non-electrically-compatible indicator panel anywhere you want, plugging into some non-historical hardware, but.. (The non-electrically-compatible indicator panel Dave did for the QSIC is initially being used in something which emulates an RK11 and/or RP11, so there's some rationale for it.) Noel

4 years, 1 month

NI PCI-GPIB+ Analyzer boards on ebay

by rdbrown0au＠gmail.com

https://www.ebay.com.au/sch/m.html?_ssn=techparts2020&_nkw=%22PCI-GPIB%2B%22 NI National Instruments PCI-GPIB+ Analyzer PCI IEEE488.2 Interface Card (~USD140) Ebay item # 284088568161 Copyright 1998???? 183619B-01 284088565868 Copyright 2001???? 183619C-01 284088570014 Copyright 2005 ASSY192125D-01 While a photo shows the Windows NI Analyzer software in use, the item doesn't mention it. If NI will provide the analyzer software, these could be used to capture HP-IB traffic to characterize the attached devices, timings etc. The HPDrive project mentions the analyzer cards as being supported https://www.hp9845.net/9845/projects/hpdrive/#hpdrive

4 years, 1 month

PDP-11/70 Boards

by jnc＠mercury.lcs.mit.edu

> From the blog of someone who got a KB11-A working It's Fritz Mueller's blog; at about the top of this page: https://fritzm.github.io/category/pdp-116.html he's just turned the machine on for the first time, and you can follow as he chases, finds and fixes CPU problems. The KB11-C/D of the -11/70 is _very_ similar to the KB11-A he was dealing with (they are _basically_ the same CPU, with a cache, and other stuff added on the other side from the CPU, on the KB11-C/D), so there are probably some good lessons to be learned. > dunno if Guy Steele Ooops; sorry, Guy - the brain is starting to drop bits. > if the particular machine the system is being built for has an FP11). > Perhaps the later BSD versions look for the FP11 on startup, and adjust > their behaviour appropriately, but I'm not familiar with them. The way user code deals with the existence/non-existence of the FP11 is pretty simple. In C (other languages probably do something similar, but I only know about C),one gives the '-f' flag to 'cc', and when 'cc' invokes the linker, on machines which don't have floating point support, it uses fcrt0: https://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/source/s4/fcrt0.s as the machine language startup (the thing that calls main()) instead of crt0. The difference is that fcrt0 sets the UNIX 'illegal instruction' signal, in that process, to go to a handler which emulates the FP11 instructions. In V6, as distributed, the binary of all applications which use floating point are linked this way, so they will all run OK 'as is' on a machine with no floating point (including those which don't suppport any kind of FP11, such as the -11/40). When run on a machine with an FP11, there are no illegal instruction traps, and that emulator code is just never used. I'm not sure what the deal with BSD is, for machines without an FP11; fcrt0.s is still included in BSD2.9, so maybe it's still using this approach. I have this vague recollection that at some point, floating point instruction emulation was added to the kernel, removing all the signal overhead, but that might be a bogus recollection. Noel

4 years, 1 month

DEC AF01, open for offers

by cz＠alembic.crystel.com

Would anyone like to make an offer on this AF01? It's a multi-channel A/D converter for old pdp8 and pdp12's. I really don't think I need it, I just pulled it out of my closet, and I don't want to put it back in. Copy me off list. Complete, multiple MUX channels (16 A121's) the A704 and the op amp (A200)

4 years, 1 month

TU58 / DECtape II: Capstan goo

by jbglaw＠lug-owl.de

Hi! Some time ago, I got my hands on a DECtape II, though no tapes. That'll change after a long time and in a few days, even multiple tapes will come in. With that drive, I started some first tests. It's PSU seems to be all fine, providing stable 5 and 12 V. It's board's wire wrapping is in factory settings, so baud rate etc. is all known. However, when I checked the two drives capstans, they're old. One has a crack, and as things go, they feel partially either hard or gooey. Are there recommendations to exchange these for new ones? I also noticed that one of the two motors rotates quite freely (both unconnected from the board, so I'm sure they're not magnetically braked) while the other ... can be turned without any unreasonable torque, but it won't continue to spin at all. Also, when the tapes arrive, are there recommendations in case their drive belts are gone? And a final question: There are three firmware versions archived for the TU58 control board. It's a known version: jbglaw at charon:~/customers/Glaw/VAX/DECtape II$ md5sum *.bin | sort 0e5f30a960e72c9d64174a4da8f48f50 23-294E2-00.bin 5e059396f779aef9cd80bc75a36c90b2 23-089E2-00.bin 5e059396f779aef9cd80bc75a36c90b2 jbglaw-DECtapeII-ROM.bin a407fbb5aaa4823a92dd2bc374d1d3ae 23-389E2-00.bin I guess I got the oldest version? Were there board changes, or could I put in a compatible 2Kx8 ROM with any of these versions? I guess any firmware will probably work "good enough", but if I'd avoid known problems (are the differences known?), I'd rather avoid them. But after all, I'm quite happy that all the bits'n'pieces will come together in a few days. Yay! MfG, JBG --

4 years, 1 month

RK11-C indicator panel inlays?

by jnc＠mercury.lcs.mit.edu

> From: Rod Smallwood > Let me see what artwork I have I'm curious as to what you'd be able to find. Like I said, I'm pretty sure DEC never did an RK11-C inlay; the engineering drawings for the 19" indicator panel (included in the RF11 engineering drawings: http://www.bitsavers.org/pdf/dec/unibus/RF11_EngrDrws_Oct70.pdf on pp. 187-188) list many inlays, but not an RK11 one. Also, I've looked through the RK11-C manual: http://www.bitsavers.org/pdf/dec/unibus/RK11-C_manual1971.pdf but it contains no mention of an indicator panel, which it surely would if there was one. > From: Henk Gooijen > I have *two* DX11 front panels with the 144 lamps & 4 'paddle' > connections boards. ... Given you have 144 lamps panel with the RK11-C > front, what would you do to light up the lamps? Uhhh... plug the paddle boards on the end of the flat cables from the indicator panel into the pre-wired slots in the RK11-C backplane (see the RK11-C engineering drawings: http://www.bitsavers.org/pdf/dec/unibus/RK11-C_schemFeb1971.pdf pg. 36)? :-) Hence my comment that to make use of the _inlay_ I proposed to produce, one had to have an RK11-C _and_ a spare DEC indicator panel... Noel

4 years, 1 month

370 control panel

by shumaker＠att.net

up for auction (and NOT on EPAY!): what appears to be an intact? System 370 control panel in PA https://hibid.com/lot/107052050/ibm-370-145-mainframe-computer/?q=&status=o… steve

4 years, 1 month

Fwd: Siemens T100 Terminal with Paper Tape - Available

by mmcgraw74＠gmail.com

Eric, I would qualify that statement and say - I'm the Tek computer Monty :) I have a Tektronix 4052 and 4054A, plus two Tektronix 4041 (68000 based GPIB controller) computers :) Both the 4052 and 4054A also have Tektronix 401x terminal emulation at up to 9600 baud, so I don't have a use for the Siemens terminal. Monty On Wed, Dec 8, 2021 at 12:58 PM Eric Moore <mooreericnyc at gmail.com> wrote: > Holy shit Monty, you are the tek terminal Monty. > > I just posted on facebook in the tek 4051 basic group, do you know anyone > with a tek 41XX or 42XX terminal? > > -Eric > > > On Wed, Dec 8, 2021, 12:51 PM Monty McGraw via cctalk < > cctalk at classiccmp.org> wrote: > >> I have this terminal in my garage - sitting on its custom stand. >> >> I purchased it years ago, but don't have a use for it. >> >> Here is my photo of it: >> >> https://drive.google.com/file/d/1SV4-Xx7XLHIoA898ZPRC74wZv2e8YsVK/view?usp=… >> >> I'm near Houston Texas. >> >> It is too big and heavy to ship. >> >> Monty McGraw >> >

4 years, 1 month

Need picture of power supply mounted in 11/40 cabinet

by jnc＠mercury.lcs.mit.edu

> From: Marc Howard > I've got an 11/40 I'm going to start working on. Problem is that there > are two power supplies (H742 and H7420) that came with it but neither > was mounted in the rack. -11/40's in general only have one of those large H742x suppplies in a rack. The documentation and prints all show only a single one - in fact, the 11/40 power harness (which is specific to the KD11-A backplane, at the CPU end) can only attach to one. The KB11 machines (-11/45 and /70) use two, but their harness has provision for two. I don't know of a DEC document that lists the difference between the H742 and H7420, but my CHWiki page for them: https://gunkies.org/wiki/H742_Power_Supply gives what I think is a pretty good list; any errors or missing details would be appreciated. > Also how is the power cabling routed (I think I'm missing this part)? That's going to be a hassle, replacing the main harness! Especially since production of the 8-pin MATE-N-LOK connector shells used to interface to the H744/etc 'bricks' - part numbers here: https://gunkies.org/wiki/DEC_standard_modular_regulators are out of production, although some vendors have residual stocks. Hoard them while they last! The "PDP-11/40, -11/35 (21 inch chassis) system manual" (EK-11040-TM-002): http://www.bitsavers.org/pdf/dec/pdp11/1140/1140_SystemManual.pdf has pretty good coverage of the harness; the back end of Chapter 6 covers it in detail. That's a lot easier to understand than the FMPS: http://www.bitsavers.org/pdf/dec/pdp11/1140/PDP-1140_System_Engr_Drawings_R… so read that before you tackle the prints. Note that there are two different kinds of harness, depending on whether the machine has MM11-L (-15V) or MM11-U (+20V) core memory. Unless you're planning on using one of those, you can probably ignore that, though. Any questions, ask here right off; we have a lot of expertise! :-) ('My' first -11 - as in, one I was in charge of - was a -11/40. Fond mempries!) Noel

4 years, 1 month

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