🚀 go-pugleaf

On Saturday, August 11, 2018 at 10:25:17 AM UTC-4, Dan Espen wrote:

> 1401 was my first also.  One could do quite a bit in a small amount of
> storage.  The A and B registers would tell you about the data the
> previous instruction processed.  (Usually where the word mark was.)
> Word marks were like the trailing null with C strings without the bother.
> 
> A shame none of that carried over to the S/360.
> We could have had a 7 bit character with one bit reserved for the word mark.

Lots of 1401 customers simply continued with that under emulation
with their S/360, or even subsequent models for decades.

Some in IBM were opposed to S/360 and wanted to build on 1401.
Haanstra built a "super" 1401 using SLT chips.  IBM mgmt. was
annoyed by that.

Ironically, despite IBM's big hopes that S/360 would be a universal
machine for all customers, even the smallest models were too
expensive for low-end users.  IBM ended up introducing the low
cost 1130 and System/3, both were very popular.

Maybe making a cheap 1401 wouldn't have been a bad idea.

I wonder how many S/3 users programmed it in Assembler.  The
manual is out on bisavers.  FWIW, almost every S/3 and et al 
shop I knew of used RPG-n.  

Anyone ever use assembler on a S/3 et al machine?






> 
> > The first I fell in love with was the IBM System/360, thanks to a high school
> > graduation gift from a sweetheart, Germain's _Programming the IBM 360_.  One of
> > these days I'm going to put his simulator on Hercules and go through the
> > exercises just for giggles.
> 
> Likewise, my next system was S/360 and I accumulated extensive
> experience with the machine.  My first impression was that the machine
> was over-complicated, on purpose.  The lack of sector addressing on
> the disks is my best example.  After using disks for years on a 1440,
> disks became more complicated than I thought they should be.
> 3270s are another example.  A simple thing like screen addressing
> couldn't be done with row/column numbers in bytes?
> 
> The 24 bit addressing was more a failure in the programming department
> than in hardware design.  Why any programmer would attempt to use
> the high order byte for data instead of just assuming it would be
> part of the address some day is a mystery.  IBM stepped in it big
> putting a 3 byte address right in the DCB.  A DCB without a version
> number or other reliable marker.  Still a problem to this day,
> 
> I've done huge amounts of assembly programming and the instructions
> get the job done.  Issues with the base registers are easy to deal with
> once you figure out that each subroutine should have it's own base
> register, don't attempt to make all code addressible at once.
> 
> -- 
> Dan Espen