November 2023 - cctalk - classiccmp.org

imd2raw.c correction - linearizing ImageDisk images

by David Schmidt

There have been a few versions of the utility imd2raw.c floating around that will take Dave Dunfield's ImageDisk-created images (i.e. an .IMD file) and make a linear binary image devoid of any metadata. This is similar to the function of Dave's IMDU.COM program's /b switch. I've corrected a problem with the assumption that all imd2raw.c descendants to date have made: sectors that have a skew (i.e. not 1-1 interleaved) weren't linearized correctly. The skewed sectors need to be written out in "sorted" order, which is not necessarily captured/physical order. This is easily verified by comparing output from "IMDU /b" to earlier imd2raw outputs on any .IMD that has a sector skew that isn't 1, 2, 3 [...]. It's up on github here: https://github.com/RetroFloppy/imd2raw

2 days, 21 hours

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NRAO Data tapes

by Dani Werts

Hello, I'm an employee with the National radio astronomy observatory here in Socorro New Mexico. As part of our NGVLA upgrades, we are seeking to get rid of old data tapes from the tape reel days of Computing. These contain things such as the boot loaders, OS, specific collection programs and antenna movement programs. I personally would hate to see these just wind up in the literal dumpster and would like to see them sent out to a museum or an archiving body that can preserve them and keep them safe as a dynamic part of history. If anyone is interested or knows someone who would be interested in the VLAs data tape library please let me know. V/R Danielle Werts Front end engineer VLA Socorro New Mexico

5 months

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FTGH: (3) Qualstar 1260 9 track tape drives pertec interface

by js＠cimmeri.com

2 units working when properly stored a few years ago. 1 unit, parts unit. Must take all 3. Tested successfully only with a PC and a VAX. Located in Frederick, Maryland, USA

2 years, 5 months

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11/15, 11/20 systems and parts, more

by Paul Anderson

I am working on a deal which includes several PDP11/15 or 20s. I will be looking at them next week and hope to get more details. I will look for exact model numbers and configuration.At least 2 of them have non DEC silkscreens on the front panel. Also a selection of 11/05 and 11/10 including 5 1/4 box, BA11-D, and BA11-K units. If you are interested in a box or parts please email me off list. Thanks, Paul

2 years, 5 months

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PDP 11/34 or 11/04 front panel question

by Tom Hunter

The PDP 11/34 and 11/04 front panels (both operator and programmer) use a somewhat stiff plastic sheet of 1.0 mm thickness with DEC logo, model designation, labels for the keys printed on it, cut-outs for the keypad and knob and red transparent sections for LEDs and 6 digit 7-segment display. I don't know what the industry calls this type of plastic sheet? Is it a "decal"??? This plastic sheet is (was) fixed to an anodized aluminium plate (1.6 mm thickness) using some type of glue which has deteriorated so that the plastic sheet has separated from the aluminium plate. The glue looks like it has been sprayed on and has a light yellowish-brown appearance. The glue readily dissolves in ethyl-alcohol and acetone, but is unaffected by water, petrol (gasoline) and dry cleaning fluid (white spirits). I would like to glue the plastic sheet back onto the aluminium plate, but worry about damaging the plastic sheet and/or paint by the solvents in typical glues. Also some glues don't allow any adjustment once you combine the two halves of whatever you glue together. What type of plastic is this plastic sheet likely made of (polycarbonate?) and what paint was used? I am asking to determine what solvent based glues may attack either the plastic sheet or the painted surfaces. The dark grey and transparent red paints are applied to the back side of the plastic sheet, so they are vulnerable to solvent attack when glueing. I tried ethyl-alcohol in one corner which is obscured by the cast metal surround and some of the dark gray colour came off with the alcohol and gentle rubbing. Has anyone successfully glued back the plastic sheet to the aluminium plate? If yes, what type of glue did you use and how exactly did you do the operation? Any suggestions, advice or tips? Thanks and best regards Tom Hunter

2 years, 7 months

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Unknown Viewsonic monitor flashes Red-Blue-Green-White

by Van Snyder

I was given a 22-inch Viewsonic monitor. The label had been scratched off. It has four switchesd below the screen, labeled 1, 2, an up arrow, and a down arrow. When I plug it in, it flashes Red, Blue, Green, White at about one- second intervals. Pushing the buttons doesn't affect it. I haven't attached a VGA or DMI to it. Is it irreparably broken? Van Snyder

2 years, 7 months

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VT100 Monitor Board

by Rob Jarratt

Hello, As some may recall I have been working on getting a VT100 going again. I have made good progress and I think the main board is probably OK now (see here if you are interested: https://robs-old-computers.com/2023/11/19/vt100-keyboard-constant-clicking-f ault/). Possibly I still need to replace the NVRAM, but I am leaving that until I fix the problem I want to describe next. The problem is that there is no image on the screen. This is because the monitor board is not doing anything, there is no glow from the neck of the tube etc. I have found that this is because the fuse on the 12V input to the monitor board is open circuit. Of course the worry is, why? There could be a fault on the board. I have tested the transistors in circuit with a multimeter and they appear to be OK. I used a bench PSU to give the board 12V and it drew no current (with all connectors disconnected). I tried again with the round connector attached to the end of the tube and it drew about 100mA and there was a faint glow from the neck of the tube. I am hesitant just to replace the fuse and try it. I am hoping for some suggestions on how to test this safely (in particular without involving the flyback transformer) to find if there is a fault. For information, the monitor is an Elston and I pre-emptively replaced all the electrolytics on the monitor board apart from the non-polar one. Some details of what I did are here https://robs-old-computers.com/2023/10/01/vt100-ram-fault/. Although I have since realised that I didn't replace two of them because they looked like diodes. I don't think the board I have is the one in the available printsets. Thanks Rob

2 years, 7 months

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Intel 4004

by Murray McCullough

On Nov. 15, 1971 Intel commercially released the 4004 microprocessor which some consider to be the first. Nonetheless, even if not in agreement, it made possible the instrument which drives the classic-computing industry or at the very least our hobby! Happy computing. Murray 🙂

2 years, 7 months

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Re: Intel 4004

by Rick Bensene

Steve Lewis wrote: > then like the 4004, we're struggling to find evidence of actual products that > made use of them. Wasn't the 4004 used in some cash registers, street lights, or > some weighing machines? (I don't have any specific references, just recollections > from past reading) The major (and primary reason for the 4004 and the MCS-4 family existing in the first place) was Nippon Calculating Machine Co and their Busicom 141-PF electronic printing desktop calculator. NCM went to the US looking for a chipmaker (the capability for the level of integration required to make such a chipset did not exist in production form anywhere else in the world at the time), and two companies were engaged to develop a chipset for NCM, one being Intel, and the other being Computer Design Corporation. As history clearly points out, Intel won the competition, developing a chipset based on the 4004 CPU, and some peripheral chips (RAM, ROM, I/O) that ended up being the operating element of the NCM/Busicom 141-PF Calculator. The 141-PF is a very famous calculator for this reason, but is otherwise (by appearance and function) a very ordinary calculator for the time. The fact that it had "Intel Inside" (though the term didn't exist at the time), using the world's first commercially available microprocessor chipset made with MOS Large Scale Integration technology, makes the 141-PF (and the OEM copies; the NCR 18-36 and the Unicom 141). Two versions of the machine were made, one that was a four-function machine, and another that added an extra ROM that added a square root function. Other devices were subsequently developed that used the 4004 as their computing core, such as digital scales, electronic cash registers, and various other electronic devices. This was only possible because initially, Nippon Calculating Machine Co. had exclusive rights to the use of the chipset. Due to some financial difficulties, NCM renegotiated the contract with Intel, removing the exclusivity clause in return for Intel forgiving some money owed on the development of the chips. This allowed Intel to sell the chipset to the open market. Once this occurred, Intel aggressively marketed the chipset as the MCS-4 microprocessor system, providing extensive documentation, development tools, both hardware and software, and lots of support for anyone wishing to develop an electronic system based on the 4004. The Busicom 141-PF calculator and its OEM versions were the first commercially-available electronic devices that had a general-purpose microprocessor with firmware implementing the machine’s logic, and thus represent the historical benchmark. These were actual products that were sold under the Busicom brand as well as NCR and Unicom. It isn’t known how many of these machines were actually made, but enough were made that they can still (rarely, though) be found today. Nippon Calculating Machine Co. in Japan manufactured and distributed them under their Busicom brand name, as well as providing the machines with subtly changed color schemes for cabinet/keyboard to OEM customers, which would market, sell, and service them under their own brand names. Rick -- The Old Calculator Museum https://oldcalculatormuseum.com P.S. If anyone out there has one of these calculators lying around gathering dust, working or not, and would like to have it see new life as part of a museum exhibit, please get in touch with me.

2 years, 7 months

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It's been a while - retirement project

by Dave Dunfield

>>[anyone know if there's a usable web interface to CCTALK? I browse it >>through the ARCHIVE on CCTALK.COM >KenUnix - 27 Nov 7:13 p.m. >When I try and connect to it I see in the tab chinese verbiage >CCtalk ???????????-?????????????? and it tries to send me to public.hujia.104.cdn20.com Sorry, my mistake - I meant the CCTALK archives at: classiccmp.org Dave -- ---------------------------------------------------------------------------------- Search "Dave's Old Computers" see "my personal" at bottom!

2 years, 7 months

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cctalk November 2023