83Plus:BCALLs:809C
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Revision as of 13:44, 30 March 2005 by FloppusMaximus (Talk | contribs)
Synopsis
Official Name: CheckOSValidated
BCALL Address: 809C
Checks bit 0 of certificate byte 1FE0h, which is set to zero once the OS has been successfully validated.
Inputs
None
Outputs
- Z if the OS has been validated
Destroys
- AF
- OP1
Comments
Flash must be write enabled first.
This bit is used in parallel with the bytes at 0056h to flag an OS as valid. Only the bytes at 0056h are checked on startup, but this flag is used in other places where the boot code needs to check if an OS is loaded.
Note that this B_CALL does not check the bytes at 0056h, 0038h, or 0026h.
The reason for making this a B_CALL is not clear to me.
