Many people have inquired whether programs designed to "speed up"
floppy disk access (SPEED41.COM, SP40.COM) are safe to run.  There has been a
concern that the use of this type of a program would increase the wear and tear
on the disk drives and shorten their life.  This question was raised once again
by one of the callers on my BBS and his call galvanized me to investigate
and determine just what the effect of these programs is.

	The two programs mentioned above are identical.  Somewhere along the
line someone apparently renamed it.  They are both available on various BBS's.
The program looks at Interrupt 30 (located at 0000:0078) to determine the
segment and offset of the disk parameter block.  In DOS 1.0 this is located
in the ROM BIOS, but in DOS 1.1 and subsequent it is a part of DOS located at
0000:0522.  The first byte (out of eleven) of the Disk Parameter contains the
hexidecimal value CF in DOS 1.0 and DF in DOS 1.1 and subsequent.  The
speedup program changes that value to EF.

	Now let me quote from Peter Norton's book "Inside the IBM PC", page
138:

		"IBM made only two changes in the disk base (sic. parameter)
		table from DOS release 1.00 to 1.10, but they resulted in
		much faster use of the diskettes.  First they made a minor
		increase in the time allowed for the diskette drive to move
		from track to track.  In the ROM version of the table, used
		by DOS version 1.00, the time was 24 milliseconds; the new
		time, starting with DOS version 1.10, is 26 milliseconds.

		On the face of it, this change should have slightly increased
		the operating time, but it apparently was aimed at reducing
		the number of times that a diskette operation failed and had
		to be re-tried - and that speeds up access.  If you are looking
		this item up in the disk base table, it is the first half - or
		first nybble, as it is sometimes called - of the first byte
		of the table.  The original value was 12, hex C, and the DOS
		1.10 value was 13, or hex D.  This parameter is counted in
		units of two milliseconds, so the increase was 2 milliseconds,
		and the new value is 26 milliseconds."

	The SPPED411.COM or SP40.COM programs therefore further increase this
value to 28 milliseconds, causing a SLOWER operating disk drive!  However, it
apparently also further reduces the required number of retries for there is a
noticeable improvement in the speed with which the drives access data.	It
would be my surmise that these programs would place LESS stress on the disk
drives, not more, yet provide improved performance.  It is well know that IBM
designs conservatively, but this is ridiculous.

	An additional benefit is that these programs produce a MUCH quieter
running disk drive.

					John McDermott
					(D) 703-321-7441
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