View Full Version : S100 diy AM9511A-4DC FPU board

Roland Huisman
May 5th, 2017, 12:49 PM
In my Northstar Horizon I found this diy AM9511A-4DC FPU board.
Does anyone recognise the design? And for which applications were these used?
Any idea's how I can test or use the board?

38261 38262

I've seen a Northstar FPU board on bitsavers, but that design is completely different.

Regards, Roland

May 5th, 2017, 01:08 PM
The CompuPro System Support 1 manual has test code for the AM9511 (look at page 74)


- Gary

Roland Huisman
May 5th, 2017, 02:27 PM
Thanks Gary, I guess I have to draw the schematic of this board to see on which
address the fpu works. With that address I think could run the code from that manual.

I hope someone recognizes this minimal FPU setup. But, what can you do with it?
On the disks I didn't find any calculator programs. Just standard CP/M stuff...

Regards, Roland

May 5th, 2017, 02:35 PM
Or write a slow loop that reads from sequential I/O ports and put a logic probe on the chip select line.

- Gary

May 5th, 2017, 03:31 PM
I believe there was a story about rolling your own back in the Kilobaud/Microcomputing mags.

The 9511 is very slow, as I recall. The 9512 was significantly faster.