Altair 8800c S/N 13219 Build Thread

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

Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 12th, 2022, 4:10 pm

Hi all,

I think I may be the latest new person to undertake building the 8800c. If you want to know a little bit about me and my early exposure with microprocessors, read Wayne P’s first post in his 8800c build thread — describes me perfectly.

So I discovered this group, the idea of the 8800c, and the boards people have made available to make this happen, and got excited and quickly started ordering things in hopes that I wasn’t too late. I’d hate to have found out some critical components were no longer available. But that wasn’t the case and things started arriving quickly.

The first item to arrive was the clone case. Now this is the part of this post I’ve been dying to get to, since even before having access to this forum. This case — wow. Absolutely fabulous. The case is beautifully done, immaculately detailed, and is just perfect in my eyes. It’s absolutely stunningly beautiful. Those of you who don’t have one yet, I have to tell you: the case is so beautifully finished, it’s incredible. I have been taking such ultra good care of it since receiving it so as not to mar it in any way. I’d like to get the computer finished and the case still look this nice — that is my goal. Currently, there is not one single mark on it.

And the FDC+ card also came. This I had to show my kids. “Children, do you know that this is? It is a PRINTED USER’S MANUAL, complete with schematics and parts list.” This is the way it used to be back in the seventies and early eighties! It’s great! And then all the advanced features this card comes with which you can choose to use or not .. I love it.

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.

Also I bought the 2SIO card. I haven’t unwrapped this one yet but it looks to be in fine physical condition and the builder provided it with exactly my options I requested. He was helpful and supportive and very easy to talk to. Everyone was.

Everyone has been so nice and helpful already, just in acquiring parts. Thank you to all of you who provided these parts to me.

I’m looking forward to getting my machine up and running. The CPU board and backplane are completed, and I’m now working on the display board pair. I’ll post pics later.

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

Postby BillO » July 12th, 2022, 8:53 pm

Welcome! Looking forward to your build log.
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 13th, 2022, 11:01 am

Thank you!

Here are a couple of photos showing some of my progress so far. Here are the CPU board, and also a CPU I hope to use. I have had this since I was about 14 years old, so over 40 years I have miraculously held onto this. Note there is neither bar code nor www dot anything anywhere on it.

I also completed the backplane and will post photos of it next.

Sirius

CPU board top
DD3A86AF-3F9F-430D-9BDA-504D8DA31DB8.jpeg
8080 CPU board front



CPU board reverse
E358C4A6-606B-4F2B-BEE0-950FED88E1A3.jpeg
CPU Board reverse



8080A CPU
474A9395-067A-416A-A436-B41F66353492.jpeg
8080A CPU
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Re: Altair 8800c S/N 13219 Build Thread

Postby Wayne Parham » July 14th, 2022, 10:13 am

Welcome, new friend!

Absolutely love that Radio Shack processor chip.

I can just picture it hangin' on the pegs at the local Radio Shack, taking it down and paying for it at the register that had no point-of-sale system. The salesman hand-wrote the ticket, took your money and sent you on your way... For you to happily install it in your Altair today!
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 14th, 2022, 1:33 pm

Nice to have a new friend, Wayne! Nice to meet you and you nailed it: that’s exactly the way it was, complete with handwritten receipt (wish I still had THAT).

I have photos of my completed backplane here as promised, but also a question for you guys:

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.

So far, every time I thought I had a parts or construction question, I’ve found the answer in one of Mike’s excellent videos (THANK YOU Mike!). The answer to this is probably in there too and I just haven’t come across it yet.

Thanks in advance!

Now for those photos:

Backplane Top
BA5F35F1-3F53-4FB5-9075-65713168AE66.jpeg
Backplane top



Backplane reverse
9348BAA4-7F80-4BE1-A410-3A40710CB2EB.jpeg
Backplane reverse
Sirius Arcturus
 
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Re: Altair 8800c S/N 13219 Build Thread

Postby BillO » July 14th, 2022, 8:50 pm

Yeah, I love that old-school RS 8080 blister pack! Brings back memories.

Nice work so far.
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Re: Altair 8800c S/N 13219 Build Thread

Postby toml_12953 » July 15th, 2022, 4:32 am

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

Postby Sirius Arcturus » July 15th, 2022, 9:13 pm

Thank you! I’ll look into that.

I have completed the display interface board and sharing photos here. Now working on the display board.

I am getting so close! This is such a pleasure to work on. Thanks to those who made it possible.

Sirius

Interface board front
160E3B27-F974-4754-B019-59B17A3FFCA9.jpeg
Interface board front


Interface board reverse
3E835AD6-419D-4ACE-8A31-91A33DE0DC93.jpeg
Interface board reverse
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Re: Altair 8800c S/N 13219 Build Thread

Postby Sirius Arcturus » July 18th, 2022, 8:57 pm

Hi all, I wanted to show you my progress on the display board while waiting for some parts. I’m waiting for the molded connector for the power and so have not installed the LEDs yet — I don’t want them to get all bent up between now and having the final parts installed.

So in preparing for this post I was checking out my photos and I noticed, in the photo, that I got one of the switches backwards! S18. I couldn’t believe it because I checked SO many times before soldering. Obviously, I didn’t check enough.

I’m very disappointed about that. At first I considered leaving it, like I did the one resistor I got “backwards” on the CPU board. I just don’t like the way that looks but I left it.

But this switch .. it will be visible. So I’ve almost convinced myself to solder sucker it out of there and turn it around. Groan. I can’t believe it.

Right now I’m working on mounting the power supplies while I wait for the molded connector for the power on the display board. The one final piece I need for that is the molded female housing for the DC connections to the backplane. I can’t find this 6 position molded housing right now for some reason. Perhaps I’m looking in the wrong place or searching for the wrong thing. I think that is the only remaining final part standing between me and completion.

That, and turning S18 around.

9DF3FDAD-ADB5-4915-A49E-F9FE9EAFF755.jpeg
All squared up and ready to drop display board onto switches


FABF74C4-32E9-4D54-951C-4B35C1D4BB62.jpeg
Dropped over all 75 terminals on the second try!


5BDAE0E7-1C16-4394-A986-DA1EAA4B43C5.jpeg
All in! And one backwards :(
Sirius Arcturus
 
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Re: Altair 8800c S/N 13219 Build Thread

Postby AltairClone » July 18th, 2022, 11:02 pm

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.

Mike
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