Re: Address bits again, Article on new mainframe use

On 9/12/2024 2:33 PM, John Dallman wrote:

In article <20240912141925.000039f3@yahoo.com>, already5chosen@yahoo.com
(Michael S) wrote:
 

x86 Real mode segmentation is a hack to the address space. 80286
protected mode segmentation is something else. The only similarity
between the two is maximal size of segment is the same.

 Yup. 80286 segmentation is horribly complicated as compared to real mode,
and still gives you tiny segments. The only widespread OS that used it
AFAIK was OS/2 1.x, much to its disadvantage. IBM's insistence that OS/2
run on the 286 was a world-shaping mistake.
 386 mode was far more useful, and survives to the present day.
 John

The subset of 386 mode that ended up being used was just a single flat virtual address space per process with paging.
I found 286 mode very useful. We used it in an bedded system with a "DOS Extender". We made malloc() give us a fresh segment for every call, and it caught a lot of simple code bugs. Bounds checking with very low overhead.