ivan@rzsin.sin.ch (Ivan D. Reid) (09/01/89)
Does anyone know if the Atari TOS uses the hidden sector count in the boot sector, or does it just blithely assume that all disks have just the one hidden sector (i.e. the boot sector itself)? History: we have a HP-150 MS-DOS machine here, along with thousands of Ataris. Yesterday a grad student hooked up a serial line to transfer files of data from the HP to an Atari, and spent a lot of time writing programmes to communicate between the two (and byte-swap his data into Motorola format). Since the HP uses identical disks to the Atari, I decided to investigate why neither machine could read the other's disks. Using a programme I wrote a while ago, I found that the Atari could read every sector on the HP disks, and dumped the boot sector. The main differences between the HP and Atari disks are i) the HP only uses 77 tracks (just like the old 8" floppies); ii) the HP has 128 root directory entries instead of 112; iii) the HP FATs are only 3 sectors; and iv) the HP has *two* hidden sectors. Then using Michtron Utilities MUTIL I found that it wanted to start reading the directory sectors one too soon, and from the behaviour of TOS with the disk I strongly suspect that it does too. So it seems that TOS probably assumes just one hidden sector and ignores the hidden sector count. Does anyone know if this is indeed the case, and if so, has it been fixed in TOS 1.4? idr