[FWD] The mystery of reading TR-DOS floppy disks has been solved!

============================================================================== * Forwarded by Wladimir Bulchukey (500:95/462) * Region : ZX.SPECTRUM (Speccy - rulez!) * From : Roman Khroupnin, (01 Jul 02 01:17) * To: All, * Topic: The mystery of reading TR-DOS floppy disks has been solved! ============================================================================== Hi All, In short I will say the following: - There are two different versions of formatted floppies: 1. hobeta 2. everyone else :) the difference is that for some reason the hobeta always sends the head value (HEAD) (3rd command) to the controller early to zero. (the head number is still sent to the controller in the first command of the 8 command procedure). Khobeta herself, of course, does not “see” "all other" floppy disks - Another problem is the data transfer speed to the DMA chip. Khobeta uses “standard” Spectrum speeds: - for 3.5" drives - 250 kb/s - for 5.25" drives - 300 kb/s however, on floppy disks this is not always the case, so during the initialization phase controller, it would be nice to set the desired speed, do some autodetect. I made :) floppies formatted in fast mode, for example program zxform.com by D.J.Dron (supplied with a navigator with sources) "visible" at a speed of 500 kb/s... these drives do not see either the hobet or the AMD01. neither all sorts of separate readers, such as makefdi. - GPL parameter (shift length) when reading or writing a sector, likePractice shows that it plays practically no role. in IBM PC AT it is equal to 2Ah. in AMD01 it is equal to 1Bh, I left it the same (we will introduce standards :))... - when formatting, the GPLF parameter (formatting shift length) must be equal to the length used by VG93. namely: - for 3.5" drives - 3Ch - for 5.25" drives - 3Ah, states D.J.Dron. generally speaking, experiment shows that disks formatted with GPLF in the range of 20h-40h "see" all PC programs. and no matter what else I hear, track zero is unreadable!!! Some people will tell me now that there is such a gap GAP4a at the beginning of the track, which on IBM floppies is usually 80, but on TR-DOS it is so small that leads to unreadability of the first sector of TR-DOS floppy disks on most IBM drive controllers. Yes, there is such a difficulty. In response, I can say - well, teledisk reads! means you can read it! regarding practical implementation - there are some considerations, I'm experimenting... yes, besides, this problem will be relevant only if the floppy disk formatted with the FORMAT "diskname" command in TR-DOS. what can I say... NEFIGA! :))) http://www.sn.nnov.ru/forum/viewtopic.php?t=39 - ZX Spectrum Navigator forum. here are the sources of the program for reading and formatting floppy disks, as always in Pascal :) and as always, using direct programming of the controller.http://www.sn.nnov.ru/downloads/ft-trdos.exe - ready-made formatter http://www.sn.nnov.ru/downloads/ld-trdos.exe - ready-made reader ================================================================================ Excuse me... That is, sorry already, All...! Ho! With the best - Wlodek. * [] * mailto: wlblack(sign)chat.ru http://wlodeks.boom.ru * <[ZX]> * http://wlodek.newmail.ru [500:95/462@ZXNet] [2:5016 Forever] [Golyanovo] [Radio 'Retro' 88.3 MHz]