🚀 go-pugleaf

keith@ksmith.uucp (Keith Smith) writes:
: In article <1992Sep10.034104.9879@nuscc.nus.sg> eletanjm@nuscc.nus.sg (TAN JIN MENG) writes:
: >davidsen@ariel.crd.GE.COM (william E Davidsen) writes:
: >: In article <14409@goanna.cs.rmit.oz.au>, s923257@yallara.cs.rmit.OZ.AU (Chew Ming Ean) writes:
: [...]
: >
: >: 
: >:   I use both ISA and EISA, and EISA config is a royal pain in the ...
: >: ear. Under normal single user load, and particularly with DOS, you will
: >: be able to measure the boost, but probably not feel it.
: >
: >Yep. With DOS - not much diff in the normal case. One the other hand,
: >OS/2 and NT (and Solaris , and NextStep) are coming up. You might want
: >to get a [real man's OS ;-)] capable machine.
: 
: Not much real difference there either.  Most people don't buy SCSI-II
: disk arrays and such so the bus is not really a bottleneck.  Expect to
: see onboard graphics stuff soon, and local bus for video, *OR* video
: coprocessor cards (My clone Distributor sells 2 now for Windows) that
: will again reduce the ISA bus bottleneck's significance.
It is a bottle neck (in terms of disk storage) when you have Virtual 
memory and not that much physical memory. Local bus is also non standard
and expensive (presently). EISA video would be (currently) a much
cheaper method of obtaining high bandwidth for video. Note that you say
ISA is no real bottleneck and in the same breadth you mention local bus;-).
: 
: >
: >One of the very real limitations regards these 32bit OSes that has been
: >exposed by OS/2 is the 16MB physical addressing limitation of the ISA
: >bus. ie. the DMA controllers can only access up to 16MB of physical
: >memory. OS/2 on [most] ISA machines therefore uses only the bottom 16MB
: >for process memory and any memory above that for page cache!
: >
: 
: Nah, OS/2 is just broken in this respect then.  SCO & I beleive SVR4
: reserve RAM <16MB for ISA DMA and copy up if need be.  Pretty simple
: concept here IMHO.  Then you can CRAM as much RAM as you want in the box
: and still use ISA controllers.  Again,  The bottlenecks aren't the BUS,
: but generally the DISKS themselves.
OS/2 does use memory >16MB. It just uses it differently. In a sense, SCO
(and NT for that matter) use the above 16MB space as a "Process memory
cache" since they would have to copy up/down everytime there is a swap
that involves a page above 16MB. OS/2 uses the space above 16MB as a
simple cache for pages. In both cases, you still have to do copying
to/from the >16MB limit.
: 
: >: bill davidsen, GE Corp. R&D Center; Box 8; Schenectady NY 12345
: >:     I admit that when I was in school I wrote COBOL. But I didn't compile.
: >
: >jin meng
: -- 
: Keith Smith          uunet!ksmith!keith            5719 Archer Rd.
: Digital Designs      BBS 1-919-423-4216            Hope Mills, NC 28348-2201
: Somewhere in the Styx of North Carolina ...

jin meng