ELITE SERIES USER MANUAL

THEORY OF OPERATION

7.2.2. Booting

The Rana boot code automatically detects the format, whether 13 or 16 sector, and loads the initial boot sector (track 0, sector 0).

On 13 sector booting, control is immediately transferred to the second stage boot code (loaded at $300—$3FF) via a jump to $301.

On 16 sector booting, the boot sector is loaded at $800—$8FF. Following the load, byte $800 is checked to find which other sectors are to be loaded prior to transferring control to the second stage. Any additional sectors will be loaded in successive memory pages ($900, $AOO, etc).

The standard DOS 3.3 second stage boot does not require any additional sectors to be loaded under the exclusive control of the boot PROM.

Once all the required sectors have been loaded, the PROM transfers control to the second stage boot code via a jump to $801.

Both the DOS 3.2.1 and DOS 3.3 second stage boot routines re-enter the boot PROM in order to use the sector reading code it contains.

DOS 3.2.1 re-enters the PROM at $Cn5D using a 6502 JSR which requires the PROM to perform an RTS when completed.

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