March 2025 - 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

1 month, 2 weeks

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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

6 months, 1 week

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Re: Selling Off My Q-Bus Collection

by donald donaldwhittemore.com

You may want to contact Dave. I believe he is doing things with this stuff. Ex-Microsoft software engineer. On X he is <https://x.com/davepl1968/status/1683904668127358976?s=58> Dave W Plummer<https://x.com/davepl1968?s=58> ⁦‪@davepl1968‬⁩<https://x.com/davepl1968?s=58>

1 year, 4 months

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Re: DEC Unibus variants

by shadoooo

The why not use a UniBone comment has merit, what will your (FPGA) > implementation add ? > Well, I know the Unibone! Surely is a very capable system for emulation of older hardware and interfaces. Also performances are good as far as I understand (I don't have one). I have the idea of extending the concept of Unibone. The new design shall be modular, composed by: - a main board hosting the SoM and common interfaces (Ethernet, SD, USB, console) - a bus module for specific bus / machine: support could be added for DEC / Data General / other? - an interchangeable interface module for an hardware device (SMD, Pertec, floppy, RX1/2, RL01/02, other). Any kind of interface could be supported, also for example ADC, DAC, maybe video to some limits...) If you have main module and bus module, you have a similar solution to Unibone / Qbone. However if you need to change bus type, you need to swap only the bus adapter (cheaper). If you have main and interfaces modules, you can control physical devices directly, and do anything with it. For example, you can dump / restore the content of a SMD disk at bit level, no need to know the controller format, etc. Similar to Kyroflux for floppy, but MUCH faster! Alternatively, you could also emulate the device at low level (for example a generic SMD disk). If you have a set of main, bus and interface modules, you can do anything as above, plus you can emulate a controller for a specific machine for a specific device. That said, implementing "anything" would be an infinite effort, but the platform is flexible, so support could be added step-by-step. So why an FPGA? A programmable logic can implement a true digital circuit, where the PRUs in the BeagleBone are processors. This means that in an FPGA the time is always precisely determined by a clock, in PRUs it is affected by the software execution. This means that a PRU can work quite well on an asynchronous bus, provided that sample rate is sufficient, even if not constant. But for a fast synchronous interface, i.e. when time is determined by an external clock, often embedded with data, no software approach can work steadily in my opinion. One thing is true: programming an FPGA is designing a netlist, not developing a software. It can be very hard to debug sometimes, because the approach is more similar to repairing an old board with a Logic Analyzer than perform debugging in software: it's a circuit in a chip, there no step-by-step execution! Nevertheless: I'm a quite good electronic engineer, highly experienced with digital logic and FPGA, so the hardware design wouldn't be a problem. Just a matter of time. Nowadays a SoM with a smaller AMD Zynq7010/7020 (a system-on-chip including an FPGA, plus dual core CPU, lot of peripherals) doesn't cost a lot, and have a great usage flexibility. Also brute computing power is superior to older BB. Why not try? I'm open to your comments. As for the UNIBUS unobtainable transceivers: I think the best solution is to use AM26S10 for drivers, and an LVC logic powered at 3.3v for receivers. Both are active parts costing nuts. I would try this approach. Andrea

1 year, 5 months

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DEC Unibus variants

by shadoooo

Hello, I'm searching information about all existing variants of DEC Unibus in Dual/Quad/Hex flavors. I read the "UnibusSpec1979.pdf" on bitsavers, which reports a "Standard Unibus" pinout in the last pages. However in several backplanes "Small Peripheral Controller", "Modified Unibus Device" and "Extended Unibus" are supported. Maybe also other unlisted Unibus variants do exist (e.g VAX 11/730)? I also found the gunkies.org WIKI very helpful, however it is still quite difficult to compare the pinout differences (dummy proof). Where could I find a specific DEC documentation about the more recent variants, similar to the 1979 specs, but referred to SPC, MUD, EUB, ect? Big doubts: - why DEC, having defined the dual Standard pinout, had then to implement the quad SPC backplanes? - why DEC, having defined quad backplanes, had then to implement the hex (standard + SPC) or (MUD + SPC) or EUB? I mean: given that in AB all Unibus signals are present (from specifications), what is the need for CDEF? Provided that several signals are duplicated in hex pinout, the backplane will connect homologue signals together, or AB bus will always be separated from CDEF bus? My aim is to design a reprogrammable digital logic board which could be employed in any system, using 18bits address or also 22bits (i.e. for 11/24). Thanks Andrea

1 year, 5 months

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Re: Wanted : Philips PSU-B3 (or -B4?) power supply for the P3800

by Fred Jan Kraan

Tony Duell wrote: > I am working on a Philips P3800 computer, about 40 years old. It's a > multiprocessor Turbodos machine, a mix of Z80's and 80186's There is some P3500/3800 documentation online, including power supplies (Netzteile) at: https://electrickery.nl/comp/divcomp/doc/index.html Not exactly what you asked for, but related. Fred Jan

1 year, 5 months

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Wanted : Philips PSU-B3 (or -B4?) power supply for the P3800

by Tony Duell

I am working on a Philips P3800 computer, about 40 years old. It's a multiprocessor Turbodos machine, a mix of Z80's and 80186's The main problem is that I only have half the power supply. I have the PSU-M3 battery-backed memory supply, but not the logic supply. This I believe to be a PSU-B3 module, although from the circuit diagrams I have, I think a PSU-B4 would work. Outputs are +5V, +12V, -12V, +24V and maybe -5V. There's also remote on/off control, so it's not trivial to use a different power supply The base board is a 233*160mm double eurocard wth a 96 pin 0.1" pitch DIN41612 connector for the outputs and a 32 pin 0.2" pitch DIN41612 connector for the mains input. There is probably another board stacked on top of it (connected only to the baseboard, not to the backplane) and there may be a metal plate on top of the lot. Please let me know if you have any idea where to find one. -tony

1 year, 5 months

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KZCCA scsi/ethernet card - VMS driver needed

by Jim Bender

Help needed! Nemonix NXETHER41/NXSCSI41 Intraserver KZCCA DEC/Compaq KZCCA All the same board, sold under multiple brands, the most prominent listed here. Differences are mostly labeling and branding. Looking for what is turning out to be an unicorn... I have a Microvax 3100-90 with the Nemonix NXETHER41 version of the card in it. This is the "ethernet only" version of this option card. It was also available with a SCSI adapter on it. As was the case with many hardware options back in this era, this card, no matter which flavor you have needs a driver installed in VMS in order for it to function. The driver was distributed as a vmsinstal package called "VAX_SCSI" and despite the name it included the drivers for the ethernet side of the board as well as the SCSI. It appears to have had multiple versions, 1.4, 1.5 and 1.6. 1.6 is the latest I have been able to find evidence for. What I have not been able to find evidence of is the files themselves. Despite the Nemonix website still being up, it appears to be a ghost town and none of the phone numbers or email addresses work. The web archive shows some Intraserver pages from the early 2000s with links to download the files but the files themselves were not archived. And unfortunately, DEC/Compaq did not see fit to include this on the CONDIST CDs. So my plea to the community here is... does anyone have the drivers for this card or any leads to where it could be found? Thanks! Jim

1 year, 5 months

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Consignment at VCF East 2025 - April 4-6 - Wall, NJ

by Jeffrey Brace

Just a few days left to get your consignment entered into NexoPOS for VCF East 2025! https://vcfed.org/events/vintage-computer-festival-east/vcf-east-consignmen… Get your tickets here: https://events.humanitix.com/vintage-computer-festival-east-2025 Info: https://vcfed.org/events/vintage-computer-festival-east/

1 year, 5 months

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InversePhase @ VCF East - April 5 - Wall, NJ

by Jeffrey Brace

Want to know what a chiptune is? How about what a chiptune is not? You can learn a little bit about the technology, its history, how it makes sounds, how it is implemented, and the culture surrounding it at this panel. All ages and experience levels are welcome! And ... After his talk, make your own chiptunes! What’s the deal with all these 8-bit whipper-snappers and their beeps, boops, and farty bass?Want to know what a chiptune is? How about what a chiptune is not? You can learn a little bit about the technology, its history, how it makes sounds, how it is implemented, and the culture surrounding it at this panel. All ages and experience levels are welcome! @inversephase is a real human person (not a robot, as you might have heard) who writes game soundtracks and chiptune tributes for a living, runs Bloop Museum, eats pizza, and even occasionally writes Bios. INFO: https://vcfed.org/events/vintage-computer-festival-east/ TICKETS: https://vcfed.org/2025/03/16/non-member-ticket-pricing-vcf-east/ VCF East is April 4-6 2201 Marconi Road Wall, NJ 07719

1 year, 5 months

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