August 2024 - cctalk - classiccmp.org

by Brent Hilpert

1 hour, 7 minutes

14
24
0 0

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

7 hours, 21 minutes

8
26
0 0

MS-DOS

by Murray McCullough

I had not realized that 43 yrs. ago Microsoft purchased 86-DOS for $50,000 – US not Cdn. money. With this purchase the PC industry, IBM’s version thereof, began. I remember using it to do amazing things, moreso than what 8-bit machines could do! Happy computing. Murray🙂

10 hours, 39 minutes

41
72
0 0

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

12 hours, 54 minutes

2
2
0 0

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

22 hours, 41 minutes

3
2
0 0

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.

1 day, 5 hours

2
1
0 0

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

1 day, 11 hours

1
0
0 0

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 days, 8 hours

5
13
0 0

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

6 days, 3 hours

1
0
0 0

Schematic or PCB layout for MAI Jolt

by brad

Hi there,Haven't had much time for vintage computers due to my job dealing with new ones, but the odd evening I have been working on PCB replica projects.One of them is for the MAI Jolt. I recently picked up alsome NOS 6530-004s, and thought it'd be a fun replica to try. I have completed the backside in KiCAD by tracing photos of the board i found online, but unfortunately the only decent photo I was able to find of the top side has components installed, and I am not good with electrical guesswork.I don't know exactly how the JOLT was originally sold (kit? Assembled?) but I'm thinking if MAI were like most pioneers then they almost certainly would have provided a schematic to end users for modifications and troubleshooting.Does anyone know if such a thing exists? I've been searching the usual places without success.Or if anyone out there has a bare board (I know, I know heh).. and wouldn't mind sending a photo or two..BradSent from my Galaxy

6 days, 10 hours

6
6
0 0

2024

2023

2022

cctalk August 2024