erd@giza.cis.ohio-state.edu (Ethan R Dicks) (02/25/90)
I have an "enhancement" to MSH, the messydisk.device in particular. I have been trying to read DEC RX-50 5-1/4" floppies for a long time now. The drive I am using is a standard PC clone 5-1/4" drive attached to the small circuit board found in the A1010 3-1/2" drive. It works fine with AmigaDOS, CrossDOS and MSH. I want to read RX-50 floppies. The chart I have from the DEC manual looks like this... "GAP 1" GAP 1: 47 x 0x4E SYNCH: 8 x 0x00 IDAM: 3 x 0xA1 1 x 0xFE TRACK: (physical track address) SIDE: (physical side number) SECTR: (physical sector number) [Repeat once SIZE: 1 x 0x02 (512 bytes per sector) per sector ] 2 CRC: 2 CRC bytes GAP 2: 22 x 0x4E SYNCH: 12 x 0x00 DAM: 3 x 0xA1 1 x 0xFB DATA: 512 x 0xE5 2 CRC: 2 CRC bytes GAP 3: 48 x 0x4E GAP 4: 6250 minus sum of bytes up to GAP 4 x 0x4E The same chart lists PC floppies as follows... "GAP 1" GAP 1A: 80 x 0x4E SYNCH: 12 x 0x00 INDEX: 3 x 0xC2 1 x 0xFC GAP1B: 50 x 0x4E SYNCH: 12 x 0x00 IDAM: 3 x 0xA1 1 x 0xFE TRACK: (physical track address) SIDE: (physical side number) SECTR: (physical sector number) [Repeat once SIZE: 1 x 0x02 (512 bytes per sector) per sector ] 2 CRC: 2 CRC bytes GAP 2: 22 x 0x4E SYNCH: 12 x 0x00 DAM: 3 x 0xA1 1 x 0xFB DATA: 512 x 0xE5 2 CRC: 2 CRC bytes GAP 3: 64 x 0x4E GAP 4: 6250 minus sum of bytes up to GAP 4 x 0x4E As you can see, the formats are extremely familiar. I would perform the change myself, but I have Lattice, not Manx. I would be very happy to see a messydisk.device which supports that track format, and a diskette head geometry of 10 sectors/track by 1 head by 80 tracks (400kb). For someone with Manx, the change is utterly trivial, but for me, almost impossible. Once I can read the blocks on a diskette, I intend to write two new file systems for the Amiga: RT-11 format and ODS-1 or ODS-2 FILES-11 format, so that I can directly read diskettes written on PDP-11s or VAXen. The other possibility is to write tar floppies, but I still need to be able to read the sectors. Thanks much. -ethan -- Ethan R. Dicks | ###### This signifies that the poster is a member in Software Results Corp| ## good sitting of Inertia House: Bodies at rest. 940 Freeway Drive N. | ## Columbus OH 43229 | ###### "You get it, you're closer."