cb@tamarack12.timbuk (Chris Brewster) (06/18/91)
Since the new DOS has paging and task switching, I'm unclear on what is still needed from a memory manager. Is QEMM or MAX still useful? Christopher Brewster Cray Research Inc. 612: 683-5759 cb@cray.com
act@softserver.canberra.edu.au (Andrew Turner) (06/18/91)
In article <CB.91Jun17133909@tamarack12.timbuk> cb@tamarack12.timbuk (Chris Brewster) writes: > >Since the new DOS has paging and task switching, I'm unclear on what is still >needed from a memory manager. Is QEMM or MAX still useful? > At a pre-release presentation a Microsoft type stated that QEMM is viable and useful under DOS 5, MAX not mentioned. He said that although DOS 5 had the ability to load stuff high that the features of QEMM were more sophisticated. QEMM's optimise does all the hard work of figuring out the best fit for stuff to load high. It seems that you have to do a little of your own figuring out with DOS 5 - the MEM command helps with this and has new features since DOS 4. NB That you can only load one thing into each vacant spot in upper memory. So don't stick a 5k device driver into a 64k hole. Another opinion given by a more-than-happy beta tester was that he preferred to use DOS 5's memory management features as they were all part of DOS 5 - if you get my drift. I suppose if you,ve paid for QEMM certainly use it, but if you don't own a copy then certainly give DOS 5's memory management a good shake. -- Andrew Turner act@csc.canberra.edu.au Die, v: To stop sinning suddenly. -- Elbert Hubbard
act@softserver.canberra.edu.au (Andrew Turner) (06/18/91)
In article <1991Jun18.013604.22276@csc.canberra.edu.au> act@softserver.canberra.edu.au (Andrew Turner) writes: > > stuff deleted > >NB That you can only load one thing into each vacant spot in upper memory. >So don't stick a 5k device driver into a 64k hole. Another opinion given by I got it wrong/He said the wrong thing!! :^(. Just installed my brand new MSDOS 5.0 upgrade and found that you can put more than one thing into a gap. Some things seem finicky like mixing devices and exe's and sometimes when you add something new something else loads lo - a bit of fiddling gets an acceptable mix. -- Andrew Turner act@csc.canberra.edu.au Die, v: To stop sinning suddenly. -- Elbert Hubbard
jcmorris@mwunix.mitre.org (Joe Morris) (06/18/91)
cb@tamarack12.timbuk (Chris Brewster) writes: >Since the new DOS has paging and task switching, I'm unclear on what is still >needed from a memory manager. Is QEMM or MAX still useful? Both Microsoft and the memory manager vendors agree that what you get with DOS 5 is about what the third-party vendors were offering four years ago or so. The code packaged with DOS 5 does a pretty good job of military packing; the other vendors (QEMM, 386^max, etc) do a better job of grocery packing. Military packing: load up the Herky bird until the next box won't fit, close the cargo door, and dispatch. Anything which didn't make it on the first pass is left behind. Grocery packing (especially in a Volkswagen Bug): Put in all the groceries which fit; if any are left over, empty the car and try again until you find a combination in which every bag is inside the car and there's still room for the driver. Users who are really hurting for memory will still find the third-party memory managers valuable, but much of their basic function is now part of DOS. Joe
pshuang@athena.mit.edu (Ping-Shun Huang) (06/19/91)
In article <CB.91Jun17133909@tamarack12.timbuk> cb@tamarack12.timbuk (Chris Brewster) writes: > Since the new DOS has paging and task switching, I'm unclear on what is > still needed from a memory manager. Is QEMM or MAX still useful? DOS 5.0 does provide task switching, but it does not provide paging; swapping, yes, but not paging. Remember, paging is done on a fixed-sized small memory block basis (swapping is done on arbitrary segment sizes), and for i386's there is hardware support in the chip for paging 4Kb blocks, if an OS wish to implement it for virtual memory purposes. Neither DOS nor QEMM nor MAX will provide this kind of utility; however, OS/2 and Windows (?) do. -- Singing off, UNIX:/etc/ping instantiated (Ping Huang)