Altair 8800c build thread

[toml_12953]

No spacers on the LEDs? You're a lot braver than I am. My LEDs would be all over the place and look like a mess.

[Curto]

Where did you purchase your LEDs? When I search for Everlite HLMPD150A everyone seems to be out of stock.

[BillO]

I wouldn't say the exact manufacturer of the LEDs is critical at all. LEDs, especially red ones are a pretty mature technology. Any 5mm diffused lens RED would do the job. You could probably get them from 2000 different places across the world through eBay.

These would do if you are dead set on buying from western supplier: https://www.digikey.ca/en/products/deta ... 00/4490012

[Wayne Parham]

I agree, these are pretty generic red LEDs.

The ones I bought are Broadcom HLMP-D101, available at Digikey.com.

• Broadcom HLMP-D101

Digikey reports having 30,258 in stock right now.

The part I have the most trouble with is the power switch. Mouser says they won't have 'em until July.

[Wayne Parham]

I had a little time this week, so I built the front-panel interface board:

Front-panel interface board

I'm waiting on 74LS109 flip-flop chips. But other than that, the interface board is done.

I'm also waiting on the power switch and on 74LS165 shift-registers for the front-panel board. When the shift-registers arrive, I'll probably start assembly, wiring power directly rather than through the power switch. That way I can get stuff running now. Then later - when the power switch arrives - I'll solder it on and assemble everything properly.

[BillO]

Moving right along!

[Curto]

Hey Wayne,

Did you buy your CPU cards assembled? Or did you stuff them yourself? If you bought them assembled, where?

Thanks,

Curt.

[Wayne Parham]

I built them myself. Boards from Gary Kaufman, and components from "tpkirkp" on eBay.

Gary Includes build instructions with the board. The components from tpkirkp are a collection of all the parts needed to populate the board, including the CPU chip (and all others), chip sockets, all passive components and even some wire for the required jumpers. There are a few notes in the component collection worth mentioning, as they tell you where to place certain parts. So don't overlook that thinking it's just a BOM.

[Curto]

Thanks, I got my board from Gary and bought the same parts kit from tpkirkp. Being my first venture into Altair land I thought it would be nice to buy an assembled and tested CPU as a known good troubleshooting aid.

I assembled my board today, took a solid 6 hours. I appreciate your tip to pay attention to the parts kit BOM. There were some helpful explanations there that made the build go pretty easy. Gary's assembly manual was also very good.

[Ttpilot]

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Thanks, I got my board from Gary and bought the same parts kit from tpkirkp. Being my first venture into Altair land I thought it would be nice to buy an assembled and tested CPU as a known good troubleshooting aid.

I assembled my board today, took a solid 6 hours. I appreciate your tip to pay attention to the parts kit BOM. There were some helpful explanations there that made the build go pretty easy. Gary's assembly manual was also very good.

Do you have R45 and R46 reversed?

From the assembly instructions