Motorola MVME2600 Series User Manual download pdf (Page 33)

100

101

General Information

1-15

The format of the beginning of the routine is:

If you want to make use of ROMboot, you do not have to fill a

complete FLASH device. Any partial amount is acceptable, as long

as:

❏ The identifier string ÒBOOTÓ starts on a word (FLASH and

Direct spaces) or 8KB (local RAM and VMEbus spaces)

boundary.

❏ The ROMboot routine size (in bytes) is evenly divisible by 2.

❏ The length parameter (offset $8) reflects where the checksum

is, and the checksum is correct.

ROMboot searches predefined areas of the memory map for

possible routines and checks for the ÒBOOTÓ indicator. Two events

are of interest for any location being tested:

❏ The map is searched for the ASCII string ÒBOOTÓ.

❏ If the ASCII string ÒBOOTÓ is found, it is still undetermined

whether the routine is meant to gain control at power-up or

reset. To verify that this is the case, the bytes starting from

ÒBOOTÓ through the end of the routine, excluding the two

byte checksum, are run through the debugger checksum

algorithm. If the result of the checksum is equal to the final

two bytes of the ROMboot routine (the checksum), it is

Offset Length Contents Description

$00 4 bytes BOOT ASCII string indicating possible

routine; the checksum must be

valid

$04 4 bytes Entry Address Word offset from ÒBOOTÓ

$08 4 bytes Routine Length Word; includes length from

ÒBOOTÓ to and including a two-

byte checksum

$0C Length

of name

Routine name ASCII string containing routine

name

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 517 518

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Motorola MVME2600 Series User Manual Page 33

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