djb@wjh12.harvard.edu (David J. Birnbaum) (11/28/89)
Is there any way to decide among setting up ramdisks in plain
old extended memory, xms extended memory, or ems?
I have a 286 with 1M on the system board and 4M on a LIM 4.0
expansion board. The memory on the expansion board can be con-
figured as any combination of extended and expanded. I cur-
rently have it divided as 2M of each, with the expanded used by
various applications and the extended all configured as a ramdisk
(using the ramdrive.sys driver that came with my MS-DOS 3.3). I
do not use any applications that require xms.
My ramdisk is in regular extended memory largely through inertia;
the driver came with MS-DOS and I never bothered to change when the
xms standard appeared or when I got my expansion board. I have xms
and expanded memory ramdisk programs; is there any reason to use any
of these instead of my old ramdrive.sys?
Thanks for any suggestions,
--David
============================================================
David J. Birnbaum djb@wjh12.harvard.edu [Internet]
djb@harvunxw.bitnet [Bitnet]
============================================================plim@hpsgpa.HP.COM (Peter Lim) (11/29/89)
> Is there any way to decide among setting up ramdisks in plain > old extended memory, xms extended memory, or ems? > > I have a 286 with 1M on the system board and 4M on a LIM 4.0 > expansion board. The memory on the expansion board can be con- > figured as any combination of extended and expanded. I cur- > rently have it divided as 2M of each, with the expanded used by > various applications and the extended all configured as a ramdisk > (using the ramdrive.sys driver that came with my MS-DOS 3.3). I > do not use any applications that require xms. > Well, one thing I do know, if you have true hardware LIM 4.0 (or even LIM 3.2) you should use expanded memory. Simply by virtue of smaller CPU overhead. To access expanded memory, you just do some bank switching and go on from there, whereas to access extended memory in a 286 machine, you have to reset the CPU after every access (which must be done in protected mode) to get back to the real mode where DOS runs. For RAM disk, print spooler and disk cache, I think PC-KWIK is a superb product. The disk cache is very fast (especially if you turn the write-cache option on) and you can share the space among RAM disk, spooler and cache dynamically ! As a sideline, if you have true hardware LIM 4.0 then you can do some "true" multitasking using DesqView rather than just using the EMS to swap program in and out. Anyway, I have no share in the people who produced PC-KWIK and DesqView :-). Have fun.
cs4g6ag@maccs.dcss.mcmaster.ca (Stephen M. Dunn) (12/01/89)
In article <436@wjh12.harvard.edu> djb@wjh12.UUCP (David J. Birnbaum) writes:
$Is there any way to decide among setting up ramdisks in plain
$old extended memory, xms extended memory, or ems?
Yes. Put it in expanded (LIM EMS) memory. It will run faster there.
To access extended memory, you have to
a) kick the processor into protected mode
b) do the transfer
c) reset the processor (!)
because Intel didn't provide any other way to get a 286 back to real
(8086) mode after being in protected mode. This takes lots of time.
On the other hand, to access expanded memory, you have to
a) tell the EMM what page(s) you want to use
b) do the transfer
This applies to disk caches, too: if you have a choice between putting
them in extended or expanded memory, use the expanded.
--
Stephen M. Dunn cs4g6ag@maccs.dcss.mcmaster.ca
<std_disclaimer.h> = "\nI'm only an undergraduate!!!\n";
****************************************************************************
They say the best in life is free // but if you don't pay then you don't eat