Tony Duell skrev:
>> All right, I've really never looked into an architecture without an
>> accumulator.
>There aren't many microprocessors without an accumulator. But things like
>the PDP11 don't have one. I can add R1 to R3, or one memory location to
>another, or... No restriction on one of the operands being in a special
>registers.
I take it you're no big fan of load/store designs?
>> >I am not going to name any particular chips, but I think that should
>> >explain why I prevfer the 6809 to the 6502, for example.
>>
>> Because it's got more registers?
>> I think the 6809 (at a glance) seems to have a lot more special cases and
>Eh? Yes, there are some special-cases on the 6809 (MUL, for example). But
>the 6502 has many more. Heck, on the 6502 you have to use the X register
>for one kind of indrect and indexed addressing and the Y register for the
>other form (on the 6809 you can do any addressing mode with X or Y (or
>with U or S for that matter). On the 6809 you can transfer values between
>any 2 registers of the same size. On the 6502 you can't even transfer
>between X and Y without destroying the accumulator contents (IIRC).
I was specifically thinking of all the different registers and the way you
combine them. But I've not got enough experience to make any insightful
comparisons.
--
En ligne avec Thor 2.6a.
"If Linux were a beer, it would be shipped in open barrels so that anybody
could piss in it before delivery."
-- Unknown
Received on Sat Aug 18 2001 - 21:52:15 BST