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Microsoft Bookshelf CD-ROM Reference Library
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ramdrive.txt
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1987-08-31
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74 lines
RAMDRIVE PARAMETERS:
device = ramdrive.sys [bbbb] [ssss] [dddd] [/E | /A]
bbbb First numeric argument, if present, is disk size
in K bytes. Default value is 64. Min is 16. Max
is 4096 (4 Meg).
ssss Second numeric argument, if present, is sector size
in bytes. Default value is 128. Allowed values are
128, 256, 512, 1024.
NOTE: In the case of IBM PC DOS the MAX value is 512.
If 1024 is specified the device will not be installed.
This "error" is detected by DOS and is not due to
the code in RAMDrive.
The 1024 byte size is included for those MS-DOS systems
where it might be allowed.
dddd Third numeric argument, if present, is the number of
root directory entries. Default is 64. Min is 2
max is 1024. The value is rounded up to the nearest
sector size boundary.
NOTE: In the event that there is not enough memory
to create the RAMDrive volume, RAMDrive will try to make
a DOS volume with 16 directory entries. This may
result in a volume with a different number of directory
entries than the dddd parameter specifies.
/E Specifies that PC AT Extended Memory is to be used.
It is an error if /E is specified on a machine other
than IBM AT or compatible.
NOTE: Information on RAMDrive drives in PC AT extended memory
will be lost at system re-boot (warm or cold). This is
due to the fact that the IBM PC AT ROM bootstrap code
zeroes all of memory.
NOTE: There is 1k of RAMDrive overhead. That is to say,
if there are 512k bytes of extended memory, there
will be 511k bytes available for assignment to RAMDrive
drives. This 1k overhead is fixed and does not depend
on the number of RAMDrive drives installed.
/A Specifies that Above Board memory is to be used. It
is an error if the above board device driver is not
present.
NOTE: Information on RAMDrive drives in Above Board memory
will be lost at system re-boot (warm or cold). This is
due to the fact that the EMM device driver performs a
destructive test when it is installed which zeros all
of the Above Board memory.
Neither /A or /E Specifies drive is to be set up below the
640K boundary in main memory.
The RAMDRIVE.SYS program looks for memory to assign to the RAMDrive
drives by looking for functioning system RAM between the
"end of memory" as determined by the INT 12H ROM BIOS
function, and the start of the video RAM (0A000:0H).
If RAM is found by the above scan, it is assigned to
RAMDrive and managed in the same way as extended memory
is when the /E switch is used. As with /E there is
1k of RAMDrive overhead. That is to say, if there are 256k
bytes of memory above the INT 12 memory size, there
will be 255k bytes available for assignment to RAMDrive
drives. This 1k overhead is fixed and does not depend
on the number of RAMDrive drives installed.
Information on such RAMDrive drives will NOT be lost on
a "warm boot" (INT 19H or Ctrl-Alt-DEL).
If RAM is NOT found by the above scan, RAMDrive will attempt
to allocate memory for the device AS PART OF THE DEVICE.
In other words the device starts immediately after the
RAMDrive resident code.
Information on such RAMDrive drives WILL BE lost on
a "warm boot" (INT 19H or Ctrl-Alt-DEL).