Martin H. Eastburn wrote:

We had custom AT's with extended memory cards that the o.s. didn't really
know. The program we used (large company) had gotten the custom AT's with
another CAD program - and converted one to AutoCad for Engineering.

I had a sample math co-processor that made Autocad work on my XT.

Whoa that's a blast from the past!
I paid $400. in relatively uninflated dollars for a 80287 for CAD.

Ran like a rocket, it did.

--Winston