1 Mar
2015
1 Mar
'15
1:39 p.m.
On 03/01/2015 11:59 AM, Al Kossow wrote:
On 3/1/15 3:42 AM, Johnny Billquist wrote:
Oh, I KNOW why they did it, it was a VERY simple operation
to wire up
in the control logic of the CPU. But, I really like the
instruction layout of
the PDP-11, which was a VERY different paradigm, entirely!
On the PDP-5/8 and the -7, I am guessing they DON'T incr the
PC an
extra time, they set up for increment through the main
adder, and then
make a carry-in if they want to double-increment the PC.
Jon
The SKIP paradigm isn't so bad, in my mind.
It makes sense on machines with a single word order code.
Incr instruction
pointer by one and you're done. It makes much less sense
on multi-word order
codes where you have to crack the instruction to see how
far to advance the
instruction pointer.