Topic       : Pure Assembler Documentation
Author      : John Kormylo
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Subject     : Documentation/Pure Assembler
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View Ref-File[ XBRA Protocol ]

Intercepting exception vectors or BIOS jump vectors is a fairly common
practice.  The XBRA protocol makes it possible to remove a vector from
a long list of such interceptions:

  DC.L 'XBRA'     ;magic value to indicate protocol being used
  DC.L 'name'     ;optional identifier, usually a cookie name
oldvec: DC.L 0    ;location to store previous vector
myvec:            ;start of executable code

Starting with the current jump vector, one can scan back through all
the XBRA structures until you find either your own vector or a program
which doesn't use the protocol.

See also Exceptions and force_media_change().