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Old 28th May 2019, 3:45 pm   #6
TonyDuell
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Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,188
Default Re: Fun with 6502 Assembler

On the 6809 there were unconditional jumps and jump-to-subroutine instructions which took an absolute address.

There were also conditional branches (8 bit displacement so +/- 127 byes) and long branches (16 bit displacement so to anywhere in memory). There were, iIRC, uncondtional branch-to-subroutine instructions (so you could write position-independant code, if the main program and its subroutes were all moved to somewhere else in memory, the displacements needed to get to a subroutine were unchanged). And the conditional branches include 'always' and 'never'.

Yes, the BRN and LBRN were NOPs, but they also skipped one or 2 further bytes (the displacement for the branch or long branch that never occured).
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