Interested in UNIVAC 9000 Series (and IBM 360)

[Chuck Guzis]

On 11/18/2016 03:15 PM, Jon Elson wrote:

> OH, yeah!  Besides the limited instruction set, short registers only 
> half populated, etc., did you know that the 360/20 did not have an 
> adder?  It could only increment/decrement.  The data paths were only
> 4 bits wide, so to add a 3 in register A to a 5 in register B, it 
> decremented A and incremented B until A went negative.  It did this
> for each nibble.  I'm guessing a 16-bit add took over 100 us.  I'd
> ALMOST reject calling this a COMPUTER!

So not even as smart as a 1620 CADET, which did arithmetic via TLU?

I guess I could believe that for register arithmetic, but did it do the
same for memory-to-memory packed decimal operations?

--Chuck