Boot from disk
Function AddressDescription
DOS_BOOT 012ABoot from disk


Boot from Disk

This routine loads a single bootstrap sector from the disk in drive A: into memory and enters it. This is for loading games or other operating systems.

Entry Parameters


Exit Parameters

If OK:
No exit as the bootstrap has taken over
Carry false
A=Error code
BC DE HL IX corrupt, all other registers preserved.

Bootstrap environment

When the bootstrap runs with the following memory configuration:

The bootstrap sector is on side 0, track 0, sector 1 of the disk. It is loaded into memory at 0xFE00 and entered at 0xFE10. Interrupts are disabled, and SP = 0xFE00.

The sum of all bytes in the sector must equal 3 MOD 256. Byte 15 in the sector can be used to adjust the sum to achive this. Bytes 0…15 of the sector hold the disk specification.

Memory Range RAM Bank
0x00000x3FFFBank 4
0x40000x7FFFBank 7
0x80000xBFFFBank 6
0xC0000xFFFFBank 3
Last modified November 24, 2021: Start of +3DOS documentation (253d8cc)