June 2020 - vcf-midatlantic

Re: Altair can't Jump
by Jeff G 17 Jun '20

17 Jun '20

Thanks Herb, its actually my intention that since I have the real deal, to get the experience of messing with it as someone may have back in the day. For the most part, I haven't used almost any test equipment other than a logic probe and multimeter so far. I'm no stranger to test gear though, I cut my teeth learning digital electronics on a Space Invaders arcade board, which happened to be powered by an 8080. I've fixed a bunch of other boards and have some decent test gear, like a Fluke 9010A with 8080 pod, O-scopes and an HP 16500C logic analyzer. That said, I'm working on this in the house, away from the bench, under a desk lamp, and so far, no cheater toys yet. YET. (evil grin) I'm at my wits end with it though, the total echo program which is about as simple as it gets really, runs about 60 bytes that I'm entering at the front panel every time. This thing has certainly given me an honorary computer science degree, as every little error and attempt to cut a corner was thrown back at me. I can speak binary and octal fluently even in my sleep, and I've also gone over this program enough times against an opcode list to make my head hurt, and all while knowing that I'm not 100% sure that either the serial board OR the CPU is 100% operational, although I'm leaning towards the CPU being good enough as it did run the kill-the-bit game and played music through an AM radio, with no problems with ram. Even if this was on the bench, I guess I'd have to run NOPs or Port IOs and look at the bus with the LA or o-scope. If the LA didn't weight more than my car I'd have lugged it into the house by now. Hardware wise, on the serial board, I found a bad voltage regulator, replaced the 1488 and 1489 ics that were missing, and even found the -16v was even missing on the motherboard (cold solder point) . I inspected it for jumpers/mods and while it does have one, it doesn't seem to be part of the serial ports nor hurting anything. As of today, I eliminated the ram board being culprit with an DeRamp FDC+ board doing ram duties. I also learned about interrupts and initially thought that perhaps they were somehow getting enabled and processed, as my code was starting at 0 and interrupt vectors are at very low addresses, like 0008h. I messed with the EI/DI opcodes to make sure the INTE light works. I've now bumped the code up to 1000h, and added a DI opcode to it, but nothing changed. I also found one final error that was likely causing a stack issue (jumping to a push instead of the following opcode), and fixed that. NOW, what did change, is that I've sat here and single stepped the entire thing, and found it works perfectly in doing so. A character I enter is being replied back no problem, which tells me serially everything's fine Yet if I run it, I'm just getting a solid stream of garbage, although interestingly, repetitive garbage. So my next thoughts are that the bus is ringing/noisy, or perhaps there's bad buffers on either the serial board or the CPU board, as it seems that reading ports 0/1 is flaky or having a timing issue, or the serial board itself has other issues. Again, works absolutely great if I single step it all the way through. If anyone wants to look at the code, you can find it here: https://docs.google.com/spreadsheets/d/e/2PACX-1vTsNFtuSOJeGfHeCDvdB7ClGbME… It was mostly taken straight from the TU-ART manual, except I changed JR's to Jump if Zeros since JR was a Z80 opcode and not supported by 8080. Jeff

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OT: Windows 10 troubleshooting
by Jeffrey Brace 17 Jun '20

17 Jun '20

Is there a Windows 10 expert here? I'm having some issues that I have not been able to resolve with various troubleshooting methods. I have searched websites and YouTube video to no avail. Please reply off the list so that I can pick your brain for ideas. -- ========================================= Jeff Brace Vice President & Board Member, VCF East Showrunner Vintage Computer Federation http://www.vcfed.org/ jeffrey(a)vcfed.org

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Altair cant jump
by Herb Johnson 16 Jun '20

16 Jun '20

Jeffrey Golas says, he's having problems running a UART echo program on his MITS Altair. He says he's doing this and that, entering this program and code and that, and getting results or not which he doesn't understand. Well, Jeffrey Golas: you are doing the right sort of things! You are trying to understand the codes, and understand the hardware you have. You are testing one thing or another thing, and looking at results, and trying to decide "what's next? what works? what doesn't work?" That is correct. This is what one did with MITS Altairs in the era. They learned how to use them, at the binary level - like you are. They learned how the hardware worked, chip by chip, signal by signal. Why would that change NOW - if the hardware is the same, the software and front panel are the same? So: now that you have some experience and are at the limits of what you know: it's time to do some homework, to stretch your limits. Sorry, but this is actually the fun part. Re-read those MITS manuals now, and the Intel 8080 manual, and the UART manual. Learn more about how the front-panel works, and how the 8080 and the UART (whatever board it is) works. Try other UART programs, simpler ones. Use some test equipment, to see the signals on the boards! Then, toggle in more code. Check the wiring and settings on that UART board. Go where the symptoms lead you. This is the fun part! And if this isn't fun, why the hell have an Altair around? That's your call of course, but you have my opinion on the matter. I think you are doing fine. Just keep doing it. Regards, Herb Johnson -- Herbert R. Johnson, New Jersey in the USA http://www.retrotechnology.com OR .net preserve, recover, restore 1970's computing email: hjohnson AT retrotechnology DOT com or try later herbjohnson AT retrotechnology DOT info

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Looking for 10MB SyQuest Cartridges
by Alexander Jacocks 15 Jun '20

15 Jun '20

All, Does anyone have any SyQuest SQ200 cartridges that they're like to part with? I have an SQ312RD 10MB drive that I'd like to use. I'm somewhat interested in other SyQuest cartridges, as well, particularly the 44/88/200 and 135/230 cartridges, as I have one of those drives, as well. Thanks! - Alex

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Apple 1 computer - original? On Ebay
by Sentry TV 15 Jun '20

15 Jun '20

Does anybody actually believe this is 100% original and authentic? APPLE 1 Original 1976 Computer System 1st Steve Wozniak designed computer and | eBay | | | | $1500000.00 | | | | | | | APPLE 1 Original 1976 Computer System 1st Steve Wozniak designed compute... This Apple-1 is an unmodified NTI board in almost perfect condition on both front and back of the main board whe... | | |

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Re: [vcf-midatlantic] Apple 1 computer - original? On Ebay
by Sentrytv 15 Jun '20

15 Jun '20

Of course, it’s like that with cars also But the prestige is, having the original. Sent from: My extremely complicated, hand held electronic device. > On Jun 15, 2020, at 2:27 PM, Ethan O'Toole <telmnstr(a)757.org> wrote: > > >> >> It’s funny >> I do realize that Cory did verify this, >> but on eBay, really! >> it seems like somebody wants to make a ton of money and not even try to donate this to a good cause or even to the museum >> if it is real. >> My 2 cents > > Yea.... but if I had one I'd do the same thing. Would finally be able to overpay for a house using money that someone overpaid for on a computer :-) > > Just build a replica to replace it. > > Ya know? > > - Ethan

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Re: [vcf-midatlantic] Apple 1 computer - original? On Ebay
by Ethan O'Toole 15 Jun '20

15 Jun '20

[NON-Text Body part not included] "You'll earn $100.00 in eBay Bucks." WHOOT! - Ethan

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Kennett Classic Open
by Bill Degnan 14 Jun '20

14 Jun '20

Kennett Classic is now open within what appears to be the COVID-19 cautionary guidelines established by Chester County, and the state of PA. Please call ahead/make an appointment. We will honor limits to the number of visitors at any given time, require masks, and everything will be sanitized after use. Bill Degnan kennettclassic.com 126 S. Union St. Kennett Square, PA 19348 484 732 7041

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Kickstarters that I am backing
by Jeffrey Brace 14 Jun '20

14 Jun '20

16 days left: Supercade: A Visual History of the Videogame Age 1985-2001: https://www.kickstarter.com/projects/vanburnham/supercade-a-visual-history-… 23 days left: The 8-bit Wars: http://kck.st/3dgsJuW -- ========================================= Jeff Brace Vice President & Board Member, VCF East Showrunner Vintage Computer Federation http://www.vcfed.org/ jeffrey(a)vcfed.org

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3M DC 600a Data Cartridge backup
by Sentrytv 14 Jun '20

14 Jun '20

Is there anybody local to me in Edison New Jersey, that may have a way of reading a 3M DC 600a data cartridge, from a back up in 12/1991 ? It is a back up of a Maxum 286 computer I believe it was running DOS and Windows. I don’t know what program was used to back it up. I believe it an external drive was used to back it up. Unfortunately the 286 motherboard is completely corroded and I do not have the original tape drive. If anybody can help out, I’m just curious to know what’s on the tape and maybe we can put the contents onto a USB drive. I’d be willing to do this at some point when we have a workshop here in New Jersey. Mike R. Sent from: My extremely complicated, hand held electronic device.

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