Imaging TRS-80/III single-sided disks

A few more gotchas to be aware of: Some of the operating systems on TRS-80 started the sector numbering at 0. Therefore, depending on which operating systems were used, you could have sectors numbered 0 - 17 , or 1 - 18. That can be confusing if your PC can't read the first sector, but tells you that it successfully read sector #1. Model 1 TRS-DOS is SINGLE DENSITY. IMD can handle that IFF the FDC in your PC is one of the ones that supports FM/SD. NOTE: some/many? TRS-80 users installed additional hardware for double density, but the OS might still require FM/SD for track 0. Disks written on a stock model 3 for use in a model 1 are not quite the same format as model 1 disks. Model 1 TRS-DOS uses some "NON-STANDARD" DAMs (Data Address Marks). I don't know how to read those with PC FDC. But, they can be read with Catweasel, OptionBoard, or other "flux transition" boards. Or design and build a PC FDC board with a 1771 WD FDC and a WD 179x FDC just to be able to handle disks with NEC/WD incompatabilities - NOTE: that disk controller should ALSO have an NEC FDC, or you won't be able to have full PC compatability. Model 1 TRS-80 has 35 tracks. They started off using the Shugart SA-400 floppy drive, which is 35 track. I think that most/all? of their later drives could do a full 40 tracks, BUT don't count on the software supporting that. Expect 35 tracks for TRS-DOS, although most/all? of the after-market operating systems supported 40 track, and some supported double sided drives ("Gee, didn't expect THAT!"), and some users even used 80 cylinder drives, for 720K capacity. Yes, there were also hardware mods for TRS-80 to use 8" disks. Yes, you can put 3", 3.25", or 3.5" drives on a TRS-80. Not all TRS-80 diskettes were of the highest quality. Be prepared to clean the heads of your drive after you finish, and maybe periodically part way through. Some TRS-80 users considered Wabash to be "premium" diskettes. -- Grumpy Ol' Fred cisin at xenosoft.com