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DISKTIME.DOC
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1985-11-03
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DISKTIME.PAS
------------
Program DISKTIME is used to measure the average access time on the
IBM-PC/XT and the IBM-PC/AT fixed disk. It is written in Turbo Pascal 3.0 as
distributed by Borland International, 4585 Scotts Valley Drive, Scotts Valley,
California, USA, 95066. This program will not destroy the data residing on
your hard disk(s), and communicates solely through BIOS service interrupt 13h.
Comparison times are from Table 5, Page 171, No 11, Vol 10 (Nov 85) of BYTE
and are increased by 8.33 milliseconds to compensate for disk latency. If you
have problems on a compatible, then it is not as compatible as you thought...
Permission is freely given by the Author of this program to distribute
copies of the UNMODIFIED program as you see fit. Please note that you will
have to run ARC(hive) (included) to extract the sources from the library. Here
is how you should proceed to generate a copy from sources
N>arc e disktime - Extract all sources
N>turbo
TURBO PASCAL SYSTEM VERSION N.NN
COPYRIGHT (C) 1983,1984,1985 BY BORLAND INC
INCLUDE ERROR MESSAGES (Y/N)? y - Want diagnostics
LOGGED DRIVE: N
WORK FILE:
MAIN FILE:
EDIT COMPILE RUN SAVE
DIR QUIT COMPILER OPTIONS
>O - Option change
COMPILE -> MEMORY
COM-FILE
CHN-FILE
COMMAND LINE PARAMETER
c - Compile to disk
COMMAND LINE PARAMETER
q - Main menu
LOGGED DRIVE: N
WORK FILE:
MAIN FILE:
EDIT COMPILE RUN SAVE
DIR QUIT COMPILER OPTIONS
>c - Compile program
WORK FILE: disktime - Enter name
COMPILING --> N:\DISKTIME.PAS
LOGGED DRIVE: N
WORK FILE:
MAIN FILE:
EDIT COMPILE RUN SAVE
DIR QUIT COMPILER OPTIONS
q - Exit Turbo Pascal
N>
The reason I wrote DISKTIME was to demonstrate how significant the access
time is on a small computer system, and to encourage the development of
a stand-alone utility which would compensate for this. Please note that
MS-DOS allocates file space in "Clusters" of 2k blocks each, which are not
necessarily consecutive. After you have been using your hard disk for
a while, sequential file clusters will probably be scattered at random
throughout your hard disk, and the time to load a file or program will
therefore be approximately equal to (ACCESS TIME) * (NUMBER of CLUSTERS)
For the 100 kilobyte Microsoft assembler, this works out to a potential
of (73.3 milliseconds)*(50 clusters) or approximately four (4) seconds
on the IBM-PC/AT !!! Hence the urgency in my appeal for de-fragmenters.
Ideally such a disk optimization facility would be well-behaved, in that
o It would be stand-alone, not requiring operator intervention
o It would require no additional peripherals such as floppies or tape
o It would not require scratch space on the disk being optimized
o It would leave the disk in a usable state after abnormal termination
Finally, I should like to thank the authors of the ARC(hive) librarian
System Enhancement Associates
21 New Street
Wayne, N.J.
USA 07470
and to note that it is easier to use, friendlier, and produces smaller files
than the LU utility which the Turbo users group currently supports...
Sincerely,
Y.N. Miles
c/o TRIUMF
4004 Wesbrook Mall
Vancouver, B.C.
Canada, V5Y 1Z7
Ph (604) 222-1047