wales@CS.UCLA.EDU (01/27/88)
I have a Taiwanese "turbo" XT clone, with 1 megabyte of RAM on the
motherboard. The system is 100% IBM-compatible as far as I can tell.
The system came with MS-DOS 3.2, but I recently upgraded to MS-DOS 3.3.
I would like to use the upper 384K of the RAM as a RAM-disk.
I have tried all of the following -- with no success:
==> The RAMDRIVE.SYS driver that comes as part of MS-DOS 3.3.
==> With the /E switch, it complains that my system is not an AT.
==> With the /A switch, it complains that an "Above Board Manager"
is not present.
==> Without either /E or /A, it ignores the extra 384K entirely and
allocates the RAM-disk out of the 640K of regular RAM.
==> The three PD RAM-disk drivers on SIMTEL20.ARPA:
PD1:<MSDOS.DSKUTL>RAMDISK.LBR
PD1:<MSDOS.SYSUTL>RAMDISK.ARC
PD1:<MSDOS.SYSUTL>RAMDISK2.ARC
All of these ignore the extra 384K and allocate the RAM-disk out of
the 640K of regular RAM.
A RAM-disk driver that does use the extra 384K was supplied by the manu-
facturer. However, if I try using it, various other things stop working
(e.g., the cursor assumes a weird shape, and keyboard sequences with
"ALT" don't work any more). I don't know whether the problem is due to
an incompatibility between the MS-DOS 3.2 that the system came with and
the MS-DOS 3.3 I have upgraded to, or whether the manufacturer's driver
never worked at all (strange as it might seem, I never tried using the
RAM-disk before now).
Can anyone out there offer any assistance?
Please note that the extra 384K is on the motherboard -- *not* on a sep-
arate card. The (very sketchy and barely decipherable) documentation
that came with my system explains that the extra 384K is accessed by
sending a signal to a specific I/O port which causes the addressing of
the two 512K-byte halves of the RAM to be swapped. I'm not familiar
enough with the PC architecture to know whether this type of scheme is
standard or not; any comments in this area would be welcomed.
-- Rich Wales // UCLA Computer Science Department // +1 (213) 825-5683
3531 Boelter Hall // Los Angeles, California 90024-1596 // USA
wales@CS.UCLA.EDU ...!(ucbvax,rutgers)!ucla-cs!wales
"Sir, there is a multilegged creature crawling on your shoulder."