test-drb

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101090 discussions

by roger.holmes＠microspot.co.uk

If anyone here has bought/is going to buy any of the ICT computer tapes from eBay (current item number 380177625923), then I probably have the only machine in the world that can read them. As I already have about 300 of these, I'm not willing to shell out 20 pounds each for them, and they may be blank anyway. However I might be missing out on data that is on them, so if either you would like to know what's on them or don't mind giving me the chance to read them then I would be vary happy to do so. You might be thinking they are standard 7 track of 9 track tapes. They aren't. They fit the Ampex TM4 drives fitted to the ICT 1300/1301/1302 (and also to the Leo 3 I think) and are ten track devices with (for the computer industry), non standard hubs. The hubs are the audio/video standard hubs, and I suspect some buyers think they are 1/4 inch audio tapes as the vendor does not spell out that they are 1/2 inch (though I questioned this and they are 1/2 inch). I suppose they will make interesting ornaments for the wall. As they've no labels they're probably blank, but who knows, they might contain the holy grail of a copy of the 1302 Executive. Roger Holmes Owner of 'Flossie' the worlds last working ICT 1301, delivered to the University of London 1962 for administration, like grading exam results and printing certificates.

16 years, 5 months

MR-78 programs for a DEC VT-78?

by ethan.dicks＠gmail.com

Hi, All, After years of looking, thanks to a tip from this list, I finally have a VT-78 to play with. I got a complete WPS-78 system except for the cart - CPU, RX78 floppy enclosure, and DEC-badged Diablo Hytype? II daisywheel printer and all the cables. So far, everything checks out. The CPU came with an MR-78 ROM pack on it. For those that might not know, it's an optional bolt-on firmware box that attaches to a DB25 plug and simulates a high-speed papertape reader. From reviewing the MR-78 printset (at the end of some of the electronic copies of the VT-78 printset), it appears that DEC sold it with several sets of firmware - there's at least a WPS78 load and a diagnostic firmware load, and possibly one or two more. Are there any ROM dumps of the MR-78 anywhere? In all my years of collecting PDP-8 parts and software and docs, I've never seen any, but I might as well ask. The circuit is utterly trivial to reproduce, and, of course, the size of modern ROMs would make it a no-brainer to make an uber-MR-78 with all known versions of the firmware on it, or with user-definable content as well (the code is stored as 8-bit bytes simulating a papertape stream (either BIN or RIM (have to check the "panel ROM code" to see which one) with some functionality removed (no RUBOUT, no pauses, and such)). Obviously I can dump the one I have, but it would be interesting to review the contents of the others. Thanks for any pointers on the MR-78 and its contents. -ethan

16 years, 5 months

Kenbak PCB wanted

by jdr_use＠bluewin.ch

There have been various successful attempts at recreating the Kenbak. If anyone has a spare PCB for sale, I'd be interested. Jos Dreesen

16 years, 5 months

Kenbak PCB

by jos.dreesen＠bluewin.ch

There have been various successful attempts at recreating the Kenbak. If anyone has a spare PCB for sale, I'd be interested. Jos Dreesen

16 years, 5 months

Tektronix 4225 -- is it an X terminal?

by andreas＠haertel-net.de

Hi, I?ve found this thread when googled the web. I?ve got a TEK 4225 also, but there isn?t any docs anywhere. The graphics functions work fine over serial line with my MicroVAX. But no more information about the AUI interface and its setup exists in web. Have you got something else in the meantime? cheers Andreas

16 years, 5 months

Software/documentation for the LSI-11 inside a Bridgeport Series II CNC milling machine?

by ethan.dicks＠gmail.com

Hi, All, I was helping someone in town with some motor issues on their circa-1980 Bridgeport CNC mill for which they fortunately have many original docs. I was tremendously surprised to find that there's an LSI-11 in the heart of the CNC cabinet. The docs have schematics, register maps, etc., and even instructions for how to use the Bridgeport punched-tape-loadable diagnostics. Fortunately, this unit has the optional punched-tape reader. Unfortunately, it has no tapes. I've done some cursory looking around and little is leaping out at me (except frequent mentions of folks who have upgraded away from the original CNC package). I'm wondering if anyone on the list knows where to pick up images of the diagnostic software for this thing. Thanks for any tips or hints. -ethan

16 years, 5 months

BBC report of "first computer virus"

by cclist＠sydex.com

A tidbit about Fred Cohen and the First Ever Computer Virus on the Beeb: http://news.bbc.co.uk/2/hi/technology/8366703.stm Except that I'm thinking that "first ever" is an exaggeration. Perhaps "first ever published for review". Even the name wasn't new in 1983. Around 1973, ten years earlier, I recall a CDC Sunnyvale ops emplyee got into some mischief on the Development Center 6400 running SCOPE 3.4 by writing a rather simple program that made use of two PP calls-- RSJ, to reschedule a job and RPV the "reprieve" service, used to recover from a job-terminating error, including a normal EOJ. The net result was that the job filled up the input queue with copies of itself and any attempt by the operator to kill it would simply spawn more copies. I seem to remember that the message displayed by the job was "You have caught a virus" or something similar. The only way out of the mess was to initiate a non-recovery deadstart of the system and then sort through jobs submitted for running before resubmitting them to find the culprit. I don't recall the name of the employee or what division he worked for; only that the COMSOURCE people wanted his head on a pike. This was about the time of one of many layoffs, so the guy may have been a short-timer anyway and just wanted to fire a parting shot. Does anyone else have a similar (earlier) story? --Chuck

16 years, 5 months

Hard-sector discs -- how many sectors?

by Watzman＠neo.rr.com

The Processor Technology SOL-20 with a semi-working Helios Disk System whose listing I am start this evening (Thurs, 11/19, at about 10pm EST) on E-Bay uses 8" 32-sector hard sector diskettes (and comes with two boxes of them). Wang systems also used these same diskettes, but, oddly, what we call the "back" of the diskettes was the "front" on Wang systems; they inserted them into the drive backwards by normal standards. The drive in the Helios is a Persci drive, just jumpered differently than for soft-sector use. There is (or was) also a very rare and unusual 32-sector 8" hard sector diskette where the sector holes were at the outer edge of the diskette circumference. Not sure who used this, but I know it existed. I believe that there was also a 16-sector 8" diskette, but I'm not sure. The number of sectors is related to sector size (Duh !!). In fact, the Helios, which had hardware variable sector sizes, defaults to using only every other sector hole and double-size sectors (in other words, I believe that it effectively has 16 sectors of 256 bytes per track, even though the diskette has 32 sector holes). By having fewer larger sectors, you effectively convert the otherwise lost inter-sector gaps into data space and increase the capacity of the media (this is true for soft sector as well). In the 5.25" size, I know that there was both 10-sector and 16-sector media. Heathkit/Zenith and NorthStar both used the 10-sector media. Subject: Re: Hard-sector discs -- how many sectors? On Thu, 19 Nov 2009, Philip Pemberton wrote: >> Specifically, how many sectors can you actually get on a >> hard-sectored disc? I know 10- and 16-sector discs were (are?) >> available, but were any larger sizes (e.g. 20 or 30 sectors) ever made? > Wang sometimes used 32 SPT hard-sectored > I would NOT dare to claim that any list is exhaustive. ------------------------------

16 years, 5 months

Interesting items on eBay

by wmaddox＠pacbell.net

Item # 190348608036 The seller claims this is a vintage computer from 1968. It's all been de-racked and is shown spread out on a table, local pickup only in Hudson, MA. There is a console that appears to have been part of medical instrumentation of some kind. I don't recognize the manufacturer's label that is shown, but there is a set of drawings, and the card cage appears to contain a core stack or two. Someone local might want to check it out. Item # 120492284400 These look like raw ceramic substrates similar to those used for IBM's SLT logic, but they appear to be set up with pads for larger die. Perhaps MST logic? Anway, the seller claims they are IBM material from the 1970's. There's a whole tray of them, as would be used in manufacturing. Could be interesting for the IBM mainframe collectors.

16 years, 5 months

RGB-VGA Converter -- buy or build?

by tanderberg_99＠yahoo.com

I would like to build a RGB-VGA converter but I don't know how to design one. If you have a circuit diagram, I would like to obtain it. I have an old RS6000 320H computer which has RGB 3 BNC with sync on green. It also says "separate". It also says that 1280 * 1048(something like that). The original monitor (IBM 6091-19)has H freq =63.35kHz (something like that), V = 60 Hz. Could you help me with the circuit? Thanks Chungduck Ko

16 years, 5 months

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