zeno@milton.acs.washington.edu (Sean Lamont) (10/27/89)
I am kind of curious how the non-dos format disks work, and how the boot block works into this. If the disk is nonstandard, how does the machine read it? In fact, how does it manage to read the boot block if it has not had the read-format defined? How would I go about writing my own format of data on the disk? Where is the boot block located, as a physical track/surface (for use by a disk editor to look at it) What does it do? Does anybody have a disassembly of it? Enough questions? Any expertise at all would be appreciated. Thanks.
ccplumb@rose.waterloo.edu (Colin Plumb) (10/27/89)
In article <582@milton.acs.washington.edu> zeno@milton.acs.washington.edu (Sean Lamont) writes: > I am kind of curious how the non-dos format disks work, and how the > boot block works into this. If the disk is nonstandard, how does the > machine read it? In fact, how does it manage to read the boot block if > it has not had the read-format defined? How would I go about writing my > own format of data on the disk? There are two layers of formatting imposed on a disk. One divides it into sectors, and is handled by the SCSI controller, trackdisk.device, or whatever. On top of that, AmigaDOS places a directory and file structure. It is possible to change either level without affecting the other, although a change to the lower level must still maintain the illusion of same-sized sectors. If you want to write something using the trackdisk.device but not the DOS file system, go right ahead. ACTION_DISABLE the file system, if any, open the trackdisk.device or whatever, and stomp away. Try to be careful not to let DOS see the result, as it might get confused. > Where is the boot block located, as a physical track/surface (for use > by a disk editor to look at it) What does it do? Does anybody have a > disassembly of it? On a floppy, blocks 0 and 1, which are located in sectors 0 and 1, track 0, side 0. The standard boot block (written by install) basically just fires up an initial CLI and starts it running the startup-sequence. I think it also initialises Intuition a bit, but I'm pretty sure Intuition is started by kickstart before loading the boot blocks. -- -Colin Plumb