8/9/2023 0 Comments Solaris formatted floppy disks![]() ![]() You have now successfully created a floppy image and overwritten the default boot-program. you CAN do this, but if you absolutely need a starting place, use the command: dd bs=1 count=378 of=myBoot.bin if=floppy.img skip=62 conv=notruncįinally, overwrite the stock MBR of the floppy with your custom myBoot.bin program: dd bs=1 count=378 if=myBoot.bin of=floppy.img seek=62 conv=notrunc ![]() The default program prints, a message, waits for a key, and then reboots.Ĭreate a file called myBoot.bin with a 378 byte x86 binary program. įrom offset 62, the next 378 bytes are yours to write your bootstrap. The Amiga needs the 880K and the PC only formats to 720K. You cannot transfer an ADF without a HD external XL drive. ![]() The first 3 bytes "eb 3c 90" are machine language for: JMP 3E \ NOP, meaning skip over the BIOS parameter block and start running the code at byte offset 62 (decimal). Use GetKick off Aminet to extract your ROM image and learn how to use an external USB drive on the PC to transfer LHA files. ![]() This creates a DOS4/OS2 compatible FAT12 disk with an extended BIOS parameter block as described at Wikipedia "Design of the FAT file system" I want to write a self-contained answer to this.įirst off, in Linux begin with your two instructions: dd if=/dev/zero of=floppy.img bs=512 count=2948 It is not called a MBR, as there is no partition table. The floppy was usable in DOS and mountable in Unix.īTW floppies have a boot sector. The additional sectors used by the secondary loader were at a fixed location on the floppy and known to the first-stage boot, which had to read/load them. The method I used for storing the secondary boot loader was to hard allocate some sectors following the root directory, and then mark those sectors as "bad" in the FAT. Two copies of the FAT are required, and then the first sector of the root directory. You cannot customize the BPB values from what MS-DOS or Windows uses for floppies.Įven though there is a value to indicate the number of sectors that the boot code occupies, every BIOS and other software I encountered (back then) only expects or tolerates one reserved sector for boot. The only thing you can really change in the floppy boot sector about 400 or so bytes of code. The error message you're seeing seems to indicate that your "boot1.bin" does not meet this requirement. Despite what various specifications might say (from Microsoft or other "experts"), the first sector of the diskette must conform to a standard MS-DOS floppy with a BIOS Parameter Block, BPB. I've actually written a two-stage floppy boot loader a long time ago (early 1990s). ![]()
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