On 2017-12-05, at 14:34:01, Seymour J Metz wrote: > The combination of a 4-bit register field and using the same registers for > accumulators, > base registers and index registers. > The alternative leads to LR pollution.
> 4 bit storage protect keys > No one would ever want to run more than 15 jobs at a time. If someone does nowadays, the correct approach is segment protection. > No address translation. Maybe paging was too expensive, but surely block > relocation > was doable. > I believe the perceived cost wasn't paging (you don't need to page if you have enough real memory), but DAT overhead. > ______________________________________ > From: Charles Mills > Sent: Monday, December 4, 2017 5:55 PM > > I believe someone (Harlan Mills? Fred Brooks?) said that he felt the only (or > most significant?) *error* in the System 360 design was the 24- rather than > 31- or 32-bit addressing. > > Anyone who has wrestled with legacy control blocks in the modern era would > probably agree. -- gil
