Altair 8800c S/N 13219 Build Thread

Discuss construction, troubleshooting, and operation of the Altair 8800c computer

Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 19th, 2022, 6:42 am

Mike,

AltairClone wrote:Don’t try to solder suck out the switch. Instead, heat all three pins at the same time as best you can (add some solder to each pin to increase heat transfer) so the switch basically drops out of the holes. Once out, then solder suck the holes clean.

Brilliant. I’m glad I slept on this because I woke up to this super recommendation. Perfect, that’s what I’m going to do. Should allow me to remove and reinstall the switch without boogering up the board — thank you!

Sirius
(Back on track)
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Re: Altair 8800c S/N 13219 Build Thread

Postby BillO » July 20th, 2022, 7:07 am

It might be and idea to snag a re-work heat gun to get that switch out in an non-destructive manner. They are inexpensive and very handy to have for other purposes too, like heat-shrink tubing.

You can get them for about $50 on Amazon.

Image
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 20th, 2022, 5:54 pm

Gee,

BillO wrote:It might be and idea to snag a re-work heat gun to get that switch out in an non-destructive manner …


I am so glad I joined this forum. In 50 years of (hobbyist) soldering I’ve never had one of these. Or even known about them! Ok, well I did get “paid to solder” a tiny amount when I was a kid, from age 12 to 16. It was the mid to late seventies and CMOS (4000 series stuff) was still fairly new (to me), and you could buy it right off the Radio Shack pegboards! And run logic circuits on a 9v battery, lol.

I have a heat gun I use for heat shrink, but I’ve seriously never even known about these. So I was pleased to wake up this morning and see this reply! I ordered right away, and now Amazon says it’s only 8 stops away. Har!

Thank you so much, BillO.

Today, with the display board still set aside, I worked on the power supply mounts. I managed to drill all seven screw holes aligned well enough that the holes in the supplies match up and they do screw into place, even the larger supply that has three holes instead of two like the smaller ones.

Also, I found some 1/4” length 4-40 screws at my local surplus electronics store which, with a washer, is perfect for use in the small supplies at the terminal end where, as Mike points out, a longer screw could contact a power lead inside the supply.

Thanks again, BillO! Looking forward to turning that switch around.

Sirius
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 29th, 2022, 7:57 pm

It’s working!

More pictures soon, I still have the power cord temp’d in and stuff like that. But it’s absolutely working.

At first it appeared it was NOT working, until I figured out I installed one of the IDC 50 connectors on the flat cable backwards. Hint: don’t do that. It won’t work.

After fixing that I was so happy to see it accept a reset. I keyed in my first program:

C3 00 00

Runs like a champ! This photo is of that program running now.

Thank you to everyone who helped. I’ll post more photos soon. BillO, that rework station made turning that switch around a snap.

This is just a quick post with more to follow soon and appropriate thanks to Mike, and to others who produced boards and those of you who helped me here.

Regards,
Sirius

6E47C9A5-36D9-4707-BA64-B6DB50236659.jpeg
8800c sn 13219 running
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Re: Altair 8800c S/N 13219 Build Thread

Postby toml_12953 » July 30th, 2022, 4:13 am

Sirius Arcturus wrote:Hi all,

I also ordered the suggested 9 slot backplane. This arrived beautifully wrapped and in excellent condition. And it is SO thick and heavy, really what you want and expect for something you are going to be plugging boards in and out of! And the mounting holes line up perfectly with the predrilled holes in the case.

Regards,
Sirius


Hmm. The predrilling must be relatively new. When I built my 8800c a few years ago, the case didn't have 'em. Good to know.
I wonder if it has the holes for the 18-slot board as well...
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Re: Altair 8800c S/N 13219 Build Thread

Postby Wayne Parham » July 30th, 2022, 10:46 am

No holes for the 18-slotter. I have one Altair with the 9-slot board and one with the 18-slot board.

I think the longest part of making an 18-slot Altair is drillin' the holes. LOL!

Anyway, great job Sirius!
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Re: Altair 8800c S/N 13219 Build Thread

Postby TheoAU » July 30th, 2022, 6:21 pm

Great job on getting it working. I'd love to see more pics.
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Re: Altair 8800c S/N 13219 Build Thread

Postby virtualaltair » September 23rd, 2022, 4:27 pm

toml_12953 wrote:
Sirius Arcturus wrote:What are folks who want one doing for an audio tape (cassette, stream, etc) interface? The options I’ve learned about so far are the 88-ARC, possibly 88-UIO, and I’m wondering also if the cassette interface for the Altair clone is an option? I would assume not, but I dunno anything about the innards of the clone.


Supposedly, the cassette interface of the Clone can be used with any serial stream. Since I'm using the 88-UIO, I never had to try it. At least it's cheap enough to experiment with and not break the bank if it fails.

If you try it and succeed, let us know what you did. I'm sure there are others who would like to use it with their 8800c.



The 88-ACR would be the most expensive option. The two-board 88-aCR solution is probably less reliable than the 88-UIO. The single board 88-UIO is nice because it has a serial port and a switch to select MITS or KCACR frequencies. That would give you three ports with your 88-2SIO (JP?). Maybe a good project for the third port would be the cassette interface for the Altair clone. A dual cassette project and maybe sell one later.
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » September 25th, 2022, 1:42 pm

Hi, Tom,

Thanks for coming here from our other thread! Yes I agree on the 88-UIO. I will keep trying and hopefully I’ll see and offered and be able to get it. I’m currently working on the VI/RTC board so I can run Timesharing BASIC and so would also love to have an additional serial port for that as an additional terminal.

You mentioned CP/M on our separate thread — I am using 2.2, but mostly Mike’s 2.2b because of the disk buffering and improved performance .. it’s really much snappier. And so I’ve even copied some of the software he has on 2.2 disk images to 2.2b disks. I’m using his FDC+ like you with TEAC 5.25” drives as Altair 8” drives. Works great.

Nice to talk to you here!

Sirius Arcturus
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Re: Altair 8800c S/N 13219 Build Thread

Postby virtualaltair » September 29th, 2022, 5:36 am

I'm using 8-inch MITS drives with the FDC+and will try Teac drives soon. I won't have time anytime soon to try an 88-UIO. The board pictures you saw were the prototype made by MITS Engineering manager Tom W. Durston. I'm not set up to use cassette. and don't know if this prototype works. A production board will probably be hard to find.
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