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Old 14 August 2018, 19:15   #14
meynaf
son of 68k
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Join Date: Nov 2007
Location: Lyon / France
Age: 46
Posts: 3,513
Quote:
Originally Posted by jotd View Post
- some instructions just froze the machine (ex: 2), after that just turn it off and on again
IIRC a NMI (that hidden button behind the oric) could get rid of this too.
Anyway, put a 65C02 in your oric and this problem is gone.


Quote:
Originally Posted by jotd View Post
I wonder (but maybe I'm wrong) if it wouldn't have been wiser to remove the "long" 10 bytes instructions and create a RISC processor from a reduced 680x0 instruction set. After all, who does "MOVE.L #$12445,$4434" nowadays? It's always possible to load a source or target register and perform the operation. At least the existing instructions would have been preserved. Intel has been doing this for decades...
It exists and is called the Coldfire. Something tells me it was quite a failure...

Anyway i kinda like the idea of doing move.l #my_cop_list,$dff080. Furthermore, in very large programs it's quite common to do move.l reloc1,reloc2 (linear access to vars).


Quote:
Originally Posted by Thorham View Post
Not really, because asr shifts in the sign bit and lsr doesn't.
Weren't we speaking about left shifts and aren't these right shifts instead ?
Anyway, shifting in the rightmost bit for the extraneous left shift would have been possible too, and, even though not exactly useful, it would have looked more balanced.
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