Re: Carry propagation, +, T=0 ???

[Penio Penev <penev@xxxxxxx>]

On Tue, 1 Apr 1997, Assen Kolov wrote:

> Penio Penev wrote:
> > 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". 
> 
> Thank you, this is indeed what happens - one should allow time 
> _before_ executing +, not after. Just consider + as a latch.
> 
> Let me quote again my manual from Offette enterprises, explaining +:
> "As the adder is implemented with ripple carry, the results of the 
> addition will not be available immediately. The sum and the carry 
> will be stabilized in the next word."

The manual may be vague, especially taking into account the non-standard
use of ALU instruction codes, i.e., latches.  The subject itself has been
beaten to death at least 5 times, and has been asked at least 30 times.
This is by far rge most-F AQ.  Someone should start writing :-) 

--
Penio Penev <Penev@pisa.Rockefeller.edu> 1-212-327-7423