Re: MISC-d Digest V97 #14

[gut@xxxxxxxxxxxxxxxxx (alex lasky)]

Begin quote:
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The rule of thumb is: carry propagates n bits for the time of one
instruction slot, where n is, I guess, 8 for P21.  Therefore, if you need
to fast carry propagation all the way up of numbers of small precision,
you should _left_ justify them, so carry starts as left as possible and
reaches T20 quickly.  Adding nops at 8 bits/nop i helpful.  You need two
nops to cover the entire possible range.  An instruction fetch from DRAM
counts as many,many nops, so plating a + in the _first_ slot in DRAM is
safe.                                           ^^^^^^^

As usual, I remind, that intructions execute in parallel, that is, if you
put a nop, the carry propagates behind the scenes.  The instruction itself
_latches_ the result of the respective unit in TOS, that is you need nops
_before_ the "instruction". 
^^^^^^^^
Penio Penev <Penev@pisa.Rockefeller.edu> 1-212-327-7423

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Isn't there a contradiction here? First you say put it in the first slot,
then you say put nops before the instruction, which implies the last slot.



Alex Lasky            * "Clubland & dubland will bop till they drop, then
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