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Old 01-16-2009, 02:19 AM
FlashCorliss FlashCorliss is offline
Junior Member
Join Date: Jan 2009
Location: Atlanta, GA
Posts: 4
Default Behold the Power of the Altair 680!

So, I got serious...

Digital Storage Scope, logic probe, DVM, 16 bit logic analyzer, PROM burner... I was going to get this fixed.

As I was getting ready to attach the logic analyzer, you know - measuring voltages and clocks, my logic probe revealed no signal on the Monitor ROM A2 line - curious. So I jumpered that pin to the socket next to it, and Voila, a "." on the terminal. I yanked the motherboard and discovered that I had missed the solder pad completely. A little dab and she's good to go.

It's a shame really. I was looking forward to using the logic analyzer:-(.

But in preparation for the surgery, I found out a lot of stuff about the Altair. Like just how funky the 1702A ROMs are, and even funkier their programming algorithim. Like how simple the Altair 680 design is, yet very complex if you don't know where the processor is going (mine was running away). And, just how awesome this kit is! Grant, you are the man!

In hindsight, stepping through the first handful of Op Codes, starting at 0xFF00, and comparing them to the source listing in the manual would have revealed the stuck (missing) A2 line. Poo

Oh well, it wasn't a complete waste of time. I got to play with my ELAB-080 that I have had for years but was still in the box. I'm kind of hoping something else will break so I can use the ELAB again.

(P.S. Grant, do you show me on your waiting list for the 8800? I can't wait to build another kit!)
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