In article , Bill Garber wrote: > What programs can I use to convert a 13 sector disk image to a real > disk? From what you wrote above the 16 sector controller should be > able to still write one? The simplest way to accomplish this would be to modify Paul Guertin's ADT such that it reads/writes only 13, not 16, sectors from each track. Since the source code to ADT is available, it's quite feasible to do this. But which Apple II emulators would be able to handle 13-sector .DSK images? The only way to deal with 13-sector disks on the emulators that I'm aware of is to store them as .NIB files. And ADT cannot handle .NIB files. One possible way would be if someone wrote an "ADT for NIB files". To read a physical disk and convert it to a .NIB file would be almost trivial: 1. Identify the beginning of the track -- the best way is probably to locate the largest block of FF self-sync nibbles. 2. Start there and read the entire track (a certain number of nibbles, this number is the same for all 5.25" GCR disks). Reading a nibble is very easy -- "Beneath Apple DOS" explains how to do it, and the code is availabine within RWTS as well -- it's just a few bytes long). 3. Send the nibbles over the serial line, and let the PC side store the data in the .NIB file. To do it the other way, i.e. transfer a .NIB file to a physical Apple II disk, is considerably harder. Reading the .NIB file from the PC, send it to the Apple and store it in a memory buffer there is the easy part. The hard part is to write that memory buffer to disk. The problem here is the timing: each nibble must be written to disk at precisely the same time interval, counted in clock cycles. I have a routine in assembler somewhere, and I can probably find it if someone wants it, which does this. I stole it from an early version of Locksmith.... :-) (version 3 something). The code which does this also needs to determine whether to write the nibbles as normal nibbles or as self-sync nibbles - a working method would be to write all FF's as self-sync nibbles and the others as normal nibbles. A self-sync nibble is an ordinary nibble, usually FF, followed by two extra zero bits; in binary this will be: 1111 1111 00). Note that an "ADT for NIB files" would be able to transfer almost any disk to a .NIB image, and back: 13-sector, 16-sector, as well as a lot of "copy-protected" disks. The only thing "ADT for NIB files" would be unable to handle is things like spiral tracks, deliberate physical defects on the disk, synchronised tracks, and various tricks with the self-sync nibbles. Also note that an "ADT for NIB files" would have no error checking. If some nibble is misread from the disk, there'll be no way to check for that. -- ---------------------------------------------------------------- Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN e-mail: pausch at stockholm dot bostream dot se WWW: http://www.stjarnhimlen.se/ http://home.tiscali.se/pausch/