-------------Original Message: Date: Sun, 11 Nov 2007 19:32:38 -0500 From: "Richard A. Cini" <rcini at optonline.net> Subject: Re: S100 Floppy Controller Question Yes, I understand the 5-for-8 substitution. One of the challenges I'm having is finding a suitable disk image to try. If I get an 8" image I plan on jamming it onto a 5.25" HD disk and giving that a whirl. I made the "8"-only" distinction because one of the boards I have (the Versafloppy) has both connectors. It just saves a little time in not having to make a cable. ------------Reply: This is quite possibly not relevant to _your_ controller, but FWIW my Cromemcos have both the DD and the HD drives on the same cable, and the 50 pin connector is only used for the 'real' 8" drive. Although some of the signals have separate drivers/receivers, the 5 1/4 and 8" drives are effectively on the same bus; the only difference is that the 8" drives supply (and the FDC expects) a /READY signal on pin 22 (?) whereas the TM-100s did not supply that signal and the FDC does not look for it on the 5 1/4" cable; I suspect that's how the system distinguishes between the drives in order to select the correct speed. Modern HD drives _do_ supply a /READY signal on pin 34, although you'll probably have to change a jumper since PCs use it for Disk Change; the jumpers are in fact often labelled DC and RDY. Therefore all that is required is a jumper on the FDC from pin 34 of the 5" connector to pin 22 of the 8" (and of course any DD 5 1/4 drives must have their /READY signal disabled if it's active). The only other FDC I have any experience with is a Micropolis, and it _does_ use the /READY signal from its DD drives (although it looks for it on pin 6, which is normally DS3 or 4), so this wouldn't work. m