On 5/11/22 10:34, Mike Katz wrote:
I don't know about TRS-DOS but a lot of early floppy disk format programs had an option to make the formatted disk bootable or not. This would copy the bootloader to the appropriate location on the floppy, copy the OS to the floppy and update any necessary pointers to the OS on the floppy.
That's what i thought, too. But I have been unable to find anything like that in any of the documentation I still have. I did find that the SYSGEN Utility under DOSPLUS may be able to that. But it may only work from floppy to floppy and not when the system is booted from a hard disk.
Usually a ROM bootloader would load a known sector (usually Track 0, Sector 0) and execute the code from that sector. That code would then get the address of the Operating System from the disk (either in a fixed location on disk or a fixed location in the directory) and load the OS.
That's the way I have always known it to be. Thus why I said if I work on a project to build boot floppies from hard disk systems I will have to have a collection of BOOT Code for the various OSes and know how they use it. I guess the first thing I will need is a program to read raw data from a floppy and another to write raw data to a floppy. This looks like a perfect job for PL/M. :-) bill
