Boot Loader for 3P+S on IMSAI

dwight dkelvey at
Tue Jan 10 15:52:33 CST 2017

When I first got my IMSAI, I had not documents. Many of the jumpers

were missing so I had to improvise. I had to write my own console in

so I chose a bit for the input buffer ready.

Of course, it was a different bit than every one else uses.

I run CP/M on it so my disgrace is berried in the low level code.

I've been meaning to patch it but then I'd have to modify all my

boot disk.

I guess, as long as it continues to work fine, what the heck.

Maybe adding a second jumper on is the trick.


From: cctech <cctech-bounces at> on behalf of william degnan <billdegnan at>
Sent: Tuesday, January 10, 2017 10:30:19 AM
To: General Discussion: On-Topic Posts
Subject: Re: Boot Loader for 3P+S on IMSAI

On Tue, Jan 10, 2017 at 1:30 PM, william degnan <billdegnan at>

> I believe this image is set to cause the 3P+S to act like a 2SIO card for
> BASIC.  NOTE:  It's set for a 20 mA current loop Teletype.  You're not
> using a teletype, so ignore related jumpers (EIA vs. 20mA current
> loop)...the rest should be correct for what you're trying to do.
> b

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