Thread: 68k details
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Old 14 August 2018, 18:52   #12
This cat is no more
jotd's Avatar
Join Date: Dec 2004
Location: FRANCE
Age: 48
Posts: 3,209
6502 on Oric was just a nightmare to code on:

- 3 8-bit registers
- 1 megahertz
- no multiplication/division (except by powers of 2 through shifting)
- additions and subtractions take the Carry flag into account. That is to propagate the carry when result is > 256. Clear it when starting an addition, set it when starting a subtraction...
- indirection only using zero page indexed (thanks to 8-bit) + one register
- some instructions just froze the machine (ex: 2), after that just turn it off and on again

I'll stick to 68000 family asm-wise!!

When motorola started with the overhyped PPC, things started to go downhill, and it became impossible to code in asm properly. You'd have to trust the compilers (which were crap at the time, now they've improved)

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...

Last edited by jotd; 14 August 2018 at 18:58.
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