Building new S100 floppy system

Richard, the Versafloppy was a fine controller for its day. Because of the 1771, it's limited to FM, and IIRC, doesn't do DMA transfers. Originally, these things were specified on single-sided media for 35 tracks. Any 5.25" 360K floppy drive can be used, provided it furnishes a READY signal--I don't recall if the Versafloppy included a optional on-board ready circuit, but it's simple enough to derive a READY signal using a couple of one-shots if your drive doesn't support one. You can use a full 40 tracks, or, alternatively, find a 720K drive like a Teac FD55F, and use 80--the 1771 doesn't care how many tracks you're using. Now, here's where my memory begins to fail after about 25+ years. I don't recall if the Versafloppy has a head-select register or not. The 1771 has no head-select logic on it, so a bit from an external latch has to furnish the signal--it seems to me that it does, but my mind could be playing tricks. If you wanted to try your hand at MFM, you could, with only a very few board changes, use a WD 2791 (which has its own data separator and head select logic on chip) which would give you both FM and MFM. Another option might be a WD 1791, but you'd have to furnish your own data separator for MFM. I wouldn't attempt this without a fast-enough CPU, however. A 4 MHz Z80 should be fine. Hope this helps. Cheers, Chuck P.S. For whatever reason, I sold the VF to a friend and bought a Tarbell controller. Still didn't do MFM, but I liked it better for some reason that now escapes me. On 5/21/2006 at 12:06 PM Richard A. Cini wrote: build