19 Dec
2008
19 Dec
'08
6:58 a.m.
Hi,
Not sure what the epithet "sequential coding" means in this context.
There is combinatoric logic elsewhere computing the new values for
these 6 latches, which take their new values at the beginning of TP4.
Your code above does not result in latches. It results in D type flipflops!
They're set on the rising edge of tp4.
You would get latches if you omit the tp4'event part of the conditional expression.
The advantage being that you didn't need to round
up all the signals
and OR them yourself :-). (I believe you do get yet more warnings,
though.)
Yes, but the goal is to minimize warnings (haha!).....
Well, that's a matter of perspective, since the
end of TS4 is just as
easily thought of as the start of TS1. Thus TP4 triggers the setting
of TS1 and initiates all the work of TS1.
Yes, of course.
if (tp4'event and tp4 = '1') then
fetch <= f_set;
defer <= d_set;
execute <= e_set;
word_count <= wc_set;
current_address <= word_count;
break <= b_set;
end if;
That's sequential coding!! every time I look at the 8/i drawings, they seem more
synchronous, so
maybe it's just that I haven't fully understood the older machines yet.
I
have my problems understanding the control and sequencing in the old machines.
Data paths are relatively clear and easy...
Philipp
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