OK, I think I have figured it out. Reading my own web site entry more carefully for Northstar….!
The original FDC was called the MDC-FDC board. It was single density 10 hard sectors/track on a 5” disk.
They later came out with a double density version called the MDS-FDC board. Still 10 sectors track on a 5” disk but now the sectors were 512 bytes/sector rather than 256.
No Western digital 17xx chip either, all done with discrete 74XX chips.
Sorry for the earlier confusion
It’s a long time ago Philip! You may be right. I thought they came out with a soft sectored FDC towards the end. The one I’m thinking of had physical wires running across top front of the board to the disk cable connector. (Looked like a bit of a kludge). I may be confusing it with somebody else. Does anybody else out there remember.
I did notice that the S100Computers.com section on NorthStar page needs correcting as the hard sectored FDC is listed 2X. Updating these boards never ends!
John Monahan Ph.D
From: n8vem...@googlegroups.com [mailto:n8vem...@googlegroups.com] On Behalf Of Nama
Are you sure?
As far as I have been able to find out, all their FDC's were all hard sectored. I think the reference to the 179x controller IC in the article you referenced is talking about competitors hardware. Maybe I'm wrong. I often am.
Not so, they made two very different FDC’s, the early ones were for hard sectored 5” disks, the later FDC was 179x driven for 8’ & 5” soft sectored disks.
John Monahan Ph.D
From: n8ve...@googlegroups.com [mailto:n8ve...@googlegroups.com] On Behalf Of Nama
This may be a long shot, but I'm in need of a Northstar S-100 floppy disk controller card. They made a few different models, but I think anything is fine for my needs.
Much thanks in advance