Xref: utzoo unix-pc.general:2809 comp.sys.att:6278 Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!csd4.milw.wisc.edu!uxc!tank!shamash!sialis!icus!lenny From: lenny@icus.islp.ny.us (Lenny Tropiano) Newsgroups: unix-pc.general,comp.sys.att Subject: 3.5" floppy disk revisited on the UNIX pc ... Keywords: 3.5" floppy, 720K, more space, backups Message-ID: <695@icus.islp.ny.us> Date: 30 Apr 89 06:08:08 GMT Organization: ICUS Software Systems, Islip, New York Lines: 46 Yes, Gil and I have done it again ... another ribbon cable coming out of our machines. (That's four cables for me, two 34 pin cables, one 20 pin cable, and a 36 pin cable for my parallel printer). It's getting a little crowded back there :-) After coming back from the Trenton Computer Festival last weekend, both with 720K 3.5" floppy disk drives (for $30 a piece), we decided to install them in our UNIX pc's. The drives are Sony Model MP-F63W-01D, 3.5" 720K floppy units. We bought them, the cases, the ribbon cable, the switch, edge connectors and the DIL connector all for about $60/each... The only "snag" we had was that the drive didn't assert the FDREADY* signal on pin 34. This caused the system to think there was no disk inserted, or the door was open, even though neither were true. Gil whipped up a little fix for that one and he grounded the FDREADY* signal only when the drive was selected. Now how did we manage to get both drives on the UNIX pc at once, since the hardware only supports one ... Well it's sorta a hack, but basically it's a mechanical switch (SPDT) that switches the FDRIVE0* signal (pin 10) between the 5.25" drive (360K) and the 3.5" drive (720K). Both cannot be accessed at the same time, but who cares ... the switch in one direction gets you original 5.25" drive that is still in the case, the other way is the 720K drive externally... It's nice to have all this space on a floppy! /floppy (/dev/fp021): 1560 blocks 190 i-nodes total: 1590 blocks 192 i-nodes (That's 814,080 bytes ... 10 sectors/track, 80 tracks)... 800K! I was able to put a floppy boot unix, floppy filesystem (all the necessary patching utilities [fsck, fsdb, etc..]) and the diagnostic program all on a 3.5" disk with a verbose loader. Ahh, no more switching disks to boot a Floppy Unix! If you want more details on the hardware aspects, I suggest you contact my hardware expert... Gil Kloepfer, Jr. (gil@limbic) -Lenny -- Lenny Tropiano ICUS Software Systems [w] +1 (516) 582-5525 lenny@icus.islp.ny.us Telex; 154232428 ICUS [h] +1 (516) 968-8576 {talcott,decuac,boulder,hombre,pacbell,sbcs}!icus!lenny attmail!icus!lenny ICUS Software Systems -- PO Box 1; Islip Terrace, NY 11752