Unless I remember wrong, expanded storage was (as already stated) composed of slower memory, and was only addressable on 4K boundaries. The simplified addressing scheme made for less expensive storage, and the timestamping made the paging algorithm work better.
J. Leslie Turriff VM Systems Programmer University of Central Missouri Room 400 Ward Edwards Building Warrensburg MO 64093 660-543-4285 660-580-0523 [EMAIL PROTECTED] >>>John Summerfield <[EMAIL PROTECTED]> 11/03/06 3:01 pm >>> David Boyes wrote: >>Is it simply a matter that the code exists for Expanded storage, so you >>continue to use it rather than write new code that could also benefit >>from the ability to write from Central to DASD directly? >>[snip] >>Put another way, couldn't an OS such as z/VM, perform better using only >>Central Storage if the code were written specifically to target Central >>storage. - Please note the word could :-) > > >Yes, it could be rewritten to assume central everywhere. Given all the other >things that are going on, this part of CP isn't broken, so it probably isn't >really high on the list of things to fix. I had thought that expanded storage, when introduced (late 80s?) was a bandaid to cover other problems. Amdahl made a great virtue of not implementing real expanded storage, though I think you could configure some central storage as expanded if you wanted. Why is expanded storage really necesary, and how is it better than having all central storage? Cheers John -- spambait [EMAIL PROTECTED] [EMAIL PROTECTED] Tourist pics http://portgeographe.environmentaldisasters.cds.merseine.nu/ Please do not reply off-list For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
