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M920 (unibus backplane jumper) to M935 (omnibus)

by Paul Anderson

Does anyone remember how this is done? Or the BC11- to the one used in 8s? Thanks, Paul

2 years

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VCF Midwest DEC "Nut" Party

by Mike Katz

For all of you who are DEC computer nuts (or aficionados) we will have our second annual DEC "Nut" pizza get together after the show at my house on Saturday (Sept 7th) after 7PM. I am unemployed so I ask all who attend to contribute to the cost of the pizza (beer and pop will be provided). Please see me at the show for my address. I hope to see you there. Mike Katz +1 (773) 414-1044 (Cell)

2 years

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A little off-topic but at least somewhat related: endianness

by Peter Ekstrom

Hi to the group, I am tinkering with some C-code where I am working on something that can process some microcode. The microcode is from a DG MV/10000 machine and while working on it, I noticed it is in little-endian. That's simple enough to work around but that had me wondering, why do we have big and little endianness? What is the benefit of storing the low-order byte first? Or is that simply just an arbitrary decision made by some hardware manufacturers? I am mostly just curious. Thanks, Peter / KG4OKG

2 years

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DEC parts at WCFMW

by Paul Anderson

If you want any DEC parts, boards, options, etc brought up to VCFMW please contact me off list. I will probably be there Saturday only and leave by 7. If you would like to stop by on the way to or from WCFMW, I should be available by appointment except Saturday. I am located about 10 miles west of Champaign, IL close to I-57, I-72, and I-74. I have PDP 8 and 11 (Qbus and Unibus) boxes, systems and parts, as well as printers and a few terminals. I have several vaxes for parts, and some 3100, 3000, and 5000- including -25, 125, 133, and 200. Please email me off list with questions,and I'll give you my # to call. I have dozens of backplanes and front panels ( including 2 11/70) and probably over 1000 boards. I also collect US and foreign coins and currency, and will take them in trade for computer gear. If anyone is driving in from the NYC/New Jersey area I need a few small things picked up there. Thanks, Paul

2 years

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Documentary on Lee Felsenstein, creator of the first video module card and Sol-20 and Osborne-1 designer

by Christian Liendo

The Daydreamer - Lee Felsenstein Legacy Technologies - Episode 02 This episode is dedicated to Lee Felsenstein, a trailblazer in the development of early personal computers during the 70s and 80s. Lee engineered the VDM-1 (Video Device Module) in 1976, the precursor to modern graphic cards. Along with figures like Steve Wozniak, he helped establish the Homebrew Computer Club, the first community for PC enthusiasts. Lee was also a co-founder of Osborne, designing the notable Osborne-1. Prior to his contributions to computing, Lee was deeply involved in the Free Speech Movement and developed “Community Memory,” a project considered the earliest form of social media. This episode celebrates Lee’s enduring impact across various communities. https://www.youtube.com/watch?v=IU7BfeXaeuE

2 years

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Re: LGP-30 (was LCM auction)

by Rick Bensene

Mark L. wrote concerning the LGP-30 computer in the LCM+L/Paul Allen Auctions: > I dare to bet it's the last one. Anywhere. It isn't the last one by any means. There are a few of these machines still around. Here are links to a few that are in collections: https://www.technikum29.de/en/computer/lgp30.php https://t-lcarchive.org/lgp-30/ http://computermuseum.informatik.uni-stuttgart.de/dev_en/lgp30/lgp30.html (was known operational in 2007) https://arstechnica.com/information-technology/2022/11/redditor-discovers-l… (Found in 2022) The LGP-30 was designed by Nuclear Physicist and Manhattan Project Team Member Stanley Frankel, who also designed a number of electronic calculators, including the SCM Cogito 240/240SR and the Diehl Combitron. An amazing thing about the LGP-30 is its relative simplicity(compared to contemporaries of the time), relying heavily on the aspects of its magnetic drum-based memory to hold the working registers as well as program storage for the machine. This means that the machine has very few flip-flops (requiring vacuum tubes), and uses a large number of inexpensive semiconductor diode logic gates for data routing and control functions. They weren't fast by any means, but were inexpensive and reliable, and required no special power or cooling, making them very popular in a wide variety of settings, from military to business. Quite a large number of them were made, and fortunately, some have survived to this day. I don't know if any of the machines that still exist are actually in running condition today, but there were a few of them that were known to be running in the decade of 2000. Rick Bensene The Old Calculator Museum https://oldcalcultaormuseum.com Beavercreek, Oregon USA

2 years

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Re: A little off-topic but at least somewhat related: endianness

by John

> From: Peter Ekstrom <epekstrom(a)gmail.com> > > I am tinkering with some C-code where I am working on something that > can process some microcode. The microcode is from a DG MV/10000 > machine and while working on it, I noticed it is in little-endian. > That's simple enough to work around but that had me wondering, why do > we have big and little endianness? What is the benefit of storing the > low-order byte first? Or is that simply just an arbitrary decision > made by some hardware manufacturers? Mostly because hardware support for dividing a word into smaller chunks (and addressing them individually) was something manufacturers added at different times, on their own initiative, and there was no agreed-upon way to do it. And since there are two obvious ways to turn a sequence of X Y-bit chunks into a word of X * Y bits and neither one is exactly "wrong," it ended up being a crapshoot as to whether manufacturers would do it the one way, or the other. (...or do something demented instead, like the PDP-11's "middle-endian" approach to 32-bit values...) And most of the debate probably came down to matters of taste; big- endian is how we write things on paper, so it seems "natural" to most people, while little-endian means that byte offset matches place value (i.e. byte 0's value is multiplied by (256 ^ 0) = 1, byte 1's value by (256 ^ 1) = 256, etc.,) so it seems "natural" to math types. That said - and I have no idea whether this actually influenced anyone's decision for any system anywhere ever - one hard advantage of little-endian representation is that, if your CPU does arithmetic in serial fashion, you don't have to "walk backwards" to do it in the correct sequence.

2 years

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Re: A little off-topic but at least somewhat related: endianness

by Paul Koning

> On Aug 15, 2024, at 1:27 PM, Michael Thompson <michael.99.thompson(a)gmail.com> wrote: > > Danny Cohen, author of "On holy wars and a plea for peace", on the left and me in the white shirt, taken in 2003. > > MIPS CPUs can be configured by the hardware to run in either big-endian or little-endian mode. Indeed, though depending on the vendor, support for one of the modes may be marginal. I remember evaluating the Raza (now Broadcom) XLR processor when it first came out. Was told it supported little endian, which we needed. Tried to configure the eval unit in little endian mode -- dead as a doornail. Asked the rep. Answer: "well, the *hardware* is designed to support it, but the power on boot configuration code is big endian only". Oh. Ended up spending a month or two converting fun stuff like DDR timing tuning loops to little endian. It did eventually work, but no thanks to the people selling the device... paul

2 years

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Harris TTL Proms..

by Holm Tiffe

Hi, in my stash of IC's Ive found a small box containing some Harris TTL Proms 75xx and 76xx. Interestingly the print is up right when the pin 1 is on the left side. I think they are pulled somewhere, otherwise they look linke new..even the pins aren't strongly rectangular..they are spread a little to the outside. I don't know what todo with them. If someone recognizes the numbers printed on them and think that he want those chips, I'll ship them worldwide for just the shipping costs. Drop me a mail, otherwise the will enter the dumpster in a week. Regards, Holm -- Technik Service u. Handel Tiffe, www.tsht.de, Holm Tiffe, Goethestrasse 15, 09569 Oederan, USt-Id: DE253710583 info(a)tsht.de Tel +49 37292 709778 Mobil: 0172 8790 741

2 years

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Looking for cleaner schematic copies for Lomas boards

by Richard Cini

All – There may be some overlap between cctalk and other lists, but I’m working on some Lomas reproduction boards, the first being the Color Magic. I’ve made two prototypes, neither of which works with the Lomas 186 board I have. It’s a very long story (working on this for more than a year on-and-off), but I borrowed a working set of boards to assist with the reproduction so I can test from a known-working configuration. What I’m looking for is a clean scan of the schematics. There are two versions floating around, neither of which is particularly clean, so I’m looking for a clean copy so I can eliminate as many points of difference as possible. If anyone can assist with this, I’d appreciate it. Thanks! Rich -- Rich Cini http://cini.classiccmp.org

2 years

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