Altair 8800c build thread

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

Re: Altair 8800c build thread

Postby Wayne Parham » August 13th, 2022, 8:01 pm

A few more pics:

As I mentioned earlier, I wasn't happy with the card guides from JM so I made new ones from the STL file linked in the previous post. Installing them requires 72 screws. I'm about 3/4 done with that in the photo below.

Altair8800c_18slot_installing_card_guides.jpg
Installing card guides on the 18-slot backpanel


You can also see the stand-offs mounted in the chassis in the photo above. I put a standoff below each card slot, but I suppose a person could do every other one or maybe even fewer than that. But to me, the hardest part is drilling all the holes and getting them all aligned. I guess you could say I was "in for a penny, so I was in for a pound."

After I finished installing the card guides, I installed the motherboard:

Altair8800c_18slot_mounting_motherboard.jpg
Backpanel mounted in chassis
Last edited by Wayne Parham on August 13th, 2022, 8:12 pm, edited 1 time in total.
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Re: Altair 8800c build thread

Postby Wayne Parham » August 13th, 2022, 8:11 pm

Here's the 18-slot system with boards installed:

Altair8800c_18slot_boards_installed.jpg
Boards installed, cables run


I have two 8800c systems, one with a 9-slot motherboard and the other with an 18-slot motherboard. I call the former "blue" and the latter one, "red." You can see why from the photo below:

Altair8800c_blue_and_red.jpg
"Red" and "Blue" ready for action


Funny thing is I even replaced the disk access LEDs on the drive connected to "blue" with blue LEDs. Not obsessive at all.

My wife got those shelves for me to use as a rack. Shelves like that work very nicely for Altairs. I suppose some folks might use the old 19-inch EIA racks commonly used for minicomputers, but Altairs weren't designed for rack mounting so I think shelves work better.

Right now, "blue" is configured to boot 1.5Mb diskettes and "red" is configured for 330Kb. Might change 'em later. For sure I want to try Mike's serial drive server setup. That's gotta be cool!
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Re: Altair 8800c build thread

Postby TheoAU » August 14th, 2022, 3:55 am

Those card guides look much better than the previous ones used. Where possible, replicating the look of the original machine adds value. Even though the parts are new, the character of the original machine is maintained. Nice work. What are you going to do with all those empty card slots?
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Re: Altair 8800c build thread

Postby AltairClone » August 14th, 2022, 7:12 am

Great looking work Wayne! Love all the attention to detail in your assembly efforts.

Mike
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Re: Altair 8800c build thread

Postby BillO » August 14th, 2022, 12:56 pm

Nice work.
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Re: Altair 8800c build thread

Postby Wayne Parham » August 14th, 2022, 1:23 pm

Thanks for the kind words, guys. Honestly, all the credit goes to Mike Douglas, Martin Eberhard, Gary Kaufman and Jerry Walker. I just built what they designed.

I mainly wanted to show the build process as "eye candy" for anyone else thinkin' about building an Altair 8800c. It helps get 'em lusty enough to pull the trigger.

The couple of little tips and tricks I found along the way were worth mention too, I think. My hope was it helps others with the tiny details that sometimes make a difference.

TheoAU wrote:What are you going to do with all those empty card slots?

I bought a handful of other cards at the same time that I bought the boards I've listed here in this thread. Just haven't mentioned them. For example, I bought a non-volatile memory board from JM Precision. It uses a battery to make it act like core memory. I also bought an SD card interface. Not sure if that one will "play nice" with the other stuff, but we'll see. And I bought some proto boards too.

I was planning to make an analog/digital I/O board for the S100 buss, something that has digital inputs, 3A digital outputs and an old-school 8-bit DAC and 8-bit ADC. Thought about maybe doing an old Votrax speech synthesizer too. But after buying the proto boards, I have since seen a few people talking about similar projects, so I might be re-inventing the wheel with that stuff. If so, I might just buy their boards instead of designing my own. We'll see.

But yeah, I think I see your point - I think you're making the point - that 18 slots aren't needed these days. If I were running 4Kb RAM boards, the 18-slotter would be useful but now, probably not.

Looks cool though. Looks like an old-school Altair. And surprisingly, the reactance from those long traces don't seem to butcher the signals, even without terminators. The 2Mhz speed no doubt helps out there.

Just gotta say,

"Real computers have front-panels!"
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Re: Altair 8800c build thread

Postby TheoAU » August 14th, 2022, 6:32 pm

I think it's a good idea having all those extra slots. It'd be a fun challenge to see how many new boards you could populate it with. Having the ability to space out boards is also useful. My original Altair has eight slots but I usually install one board every two slots, so it's effectively populated with four boards. It makes it much easier to pull boards in and out if they're spaced apart.

I've got the same idea with my 8800C. I want to buy all the new Altair reproduction boards that are out there. The JM precision battery backed up memory would be good. Also his 16K Static board. As a coincidence, years ago I bout a TDL 16K static ram board. I could never get that board to work in my original machine. But I saved all the static ram chips. They are SEMI 4200. I believe those would work on that board.
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