Rich kids are into COBOL

Jon Elson elson at
Sun Mar 1 15:39:04 CST 2015

On 03/01/2015 11:59 AM, Al Kossow wrote:
> On 3/1/15 3:42 AM, Johnny Billquist wrote:
>> 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.
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.


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