HPIM5548

I won an eBay auction for a FD-500 and J&M Disk Controller.

This Disk Controller, is the first J&M Controller, the JFD-COCO Rev-A, with the Synertek SY6591 and JDOS in a 24 Pin ROM.

Two modifications have been made to this controller:

1) JDOS seems to have compatibility Issues, so a previous owner replaced it with a Tandy ROM, it would appear to be DECB 1.1.

2) There is also Timing Issues when this controller is used with the CoCo 3, This board has been modified, by replacing the 'E' Clock signal from the 6809 with the 'Q' Clock signal. You can see the Blue Wire from Pin 7 of the Cartridge Connector to the Via next to the U17 Silk Screen legend. Also R10 has been changed to a different point on the U17 package, a 74LS00.