dcd@tc.fluke.COM (David Dyck) (08/30/88)
Any Extended Memory 'experts' out there?
Is there a accepted standard method for using and sharing extended memory?
I know of INT 15/87 to move date to/from extended memory,
and INT15/88 to obtain total extended memory size.
Is there any way to tell if another application/ram disk/etc
is using part of the extended memory?
I am using a program like VDISK that will
allow some of extended memory to be used as a ram disk.
I also want to have a driver utilize some of the unused extended memory.
If my driver is loaded before VDISK, how would I/it inform VDISK
that some of the extended memory was already in use?
And what if VDISK loaded first,
is there a way for my driver to determine how much memory VDISK was using?
Should all extended memory applications/drivers allow the
user to specify the upper/lower bounds in extended memory?
I just finished a trial and error method of trying to get
two applications that both use extended memory to co-exist
(A disk cache driver, and a ram disk).
Thanks for any information,
David Dyck
Domain: dcd@tc.fluke.COM
Voice: +1 206 356 5807
UUCP: {uw-beaver,decwrl,microsof,sun}!fluke!dcd
Snail: John Fluke Mfg. Co. / P.O. Box C9090 / Everett WA 98206scjones@sdrc.UUCP (Larry Jones) (08/31/88)
In article <5003@fluke.COM>, dcd@tc.fluke.COM (David Dyck) writes: > Is there a accepted standard method for using and sharing extended memory? No. The cleverest idea I have heard to date is to take the amount of memory you need from the END of the extended memory and establish your own INT 15 handler to correct the "total" extended memory size reported to anyone coming after you. Since not everyone follows this scheme (notably IBM's VDISK which has it's own perverse method), things which do need to be loaded before things that don't. (Of course, the amount of memory you "need" should probably be specified by the user somehow.) ---- Larry Jones UUCP: uunet!sdrc!scjones SDRC scjones@sdrc 2000 Eastman Dr. BIX: ltl Milford, OH 45150 AT&T: (513) 576-2070 "Save the Quayles" - Mark Russell
jal@valhalla.ee.rochester.edu (09/01/88)
David Dyck (dcd@tc.fluke.com) writes: >Any Extended Memory 'experts' out there? Expert, no but I use it quite a bit. >Is there a accepted standard method for using and sharing extended memory? Microsoft, Lotus, Intel and AST have published a standard called XMS 2.0 (eXtended Memory Specification) which manages extended memory (as well as other un-managed memory areas). The only implementation I know of is part of Windows 286 and is called HIMEM.SYS. A summary of the Interrupts will probably be included in the forthcoming Interrupt list and is certainly available direct from Microsoft (that's how I got mine). >Is there any way to tell if another application/ram disk/etc >is using part of the extended memory? The programs that I write that use extended memory make themselves look like VDISK and also allow the user to specify the starting address. I will be adding XMS support so things work better. BTW lately (DOS 4.0) VDISK started allocating memory from the highest address and reporting via INT 15h a smaller amount of available memory. Other programs do this also. It is a good technique if there is not a need to remove your use of the memory so other programs can have it. XMS allows relocation and reallocation of extended memory and thus is more flexible, but only works if everyone adheres to the spec and if a driver is available. >I also want to have a driver utilize some of the unused extended memory. >If my driver is loaded before VDISK, how would I/it inform VDISK >that some of the extended memory was already in use? You can make yourself look like VDISK. VDISK knows that there may be multiple VDISK's loaded and so you can make your use of VDISK look like a previously loaded VDISK. It is not fun, but I've done it and it works. >And what if VDISK loaded first, >is there a way for my driver to determine how much memory VDISK was using? Yes, you can look for a VDISK just like VDISK does and setup to use the next available portion. >Should all extended memory applications/drivers allow the >user to specify the upper/lower bounds in extended memory? I think this is a good idea until XMS becomes sufficiently available that it is no longer needed. In the meantime I intend to support both XMS and VDISK detection/faking and user specification of starting address/length. >Thanks for any information, Your welocme. If you need detailed info, I can investigate releasing some of my code.
stevewa@upvax.UUCP (Steve Ward) (09/03/88)
In article <368@sdrc.UUCP> scjones@sdrc.UUCP (Larry Jones) writes: > >No. The cleverest idea I have heard to date is to take the amount of memory >you need from the END of the extended memory and establish your own INT 15 >handler... > >Larry Jones UUCP: uunet!sdrc!scjones >SDRC scjones@sdrc >2000 Eastman Dr. BIX: ltl >Milford, OH 45150 AT&T: (513) 576-2070 The newest version of MS-Windows (Version 2.1) Includes an "Extended Memory Manager" which windows uses to store some of its buffers (?) in Extended memory. I must admit total ignorance to how it works, but it may be an indication of the "accepted way" of dealing with Extended memory, at least according to Microsoft. Maybe one of the guys up at MS will clue us all in... | Steve Ward Jr. | | | University of Portland (Just a lowly student!) | stevewa@upvax.UUCP | | Portland, Oregon | !tektronix!upvax!stevewa |