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1991-10-14
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Quick Disk Identification (QDI)
Version 2.0
October 13, 1991
Copyright 1991: George Spafford
Purpose:
To identify the basic drive hardware on an IBM compatible computer.
Procedure:
Install QDI in a directory in your path. QDI must now be invoked on the
drive to be checked. In other words, if you want information about your
E: drive, you would have to go to your E: drive and run QDI from there.
Output Definitions:
Media Descriptor: This is the hex value of the drive.
Bytes per sector: This is the number of bytes per sector.
Total Sectors: This is the total sector count for the drive.
Sectors per Cluster: This is the number of sectors in each cluster.
Bytes per cluster: This is the number of bytes in each cluster.
Total Clusters: This is the total cluster count for tthe drive.
Free Clusters: This is the number of clusters that have yet to be
allocated for storage. I.E. they are free for use.
Total Space: This is the total amount of disk space in terms of
bytes.
Free Drive Space: This is the amount of drive space that is available
for use.
Let's Talk:
Okay, a few basics may be in order. If you know about hard drives, then you
can easily skip this section and still sleep at night. Your hard disk, or any
disk drive for that matter, is composed of bits, bytes, sectors, clusters, and
other things that go bump in the night. The following is a brief attempt to
explain what some of them mean.
Byte: This is one character. The letter C is one byte.
Bit: 8 bits (sequences of 1's and 0's) make up one byte.
Sector: A sector is a group of bytes based on a power of 2.
512 bytes is quite common for drives.
Cluster: A cluster is a compilation of sectors - also based on the
power of 2.
How do they relate you ask??
Total Bytes Per Cluster = Bytes per Sector * Sectors Per Cluster
Total Drive Space = Bytes per sector * Sectors per cluster * Total Clusters
Bytes per Cluster = Total Drive Space in Bytes / Total Clusters
Why I am telling you this???
You see, the old PC has a small limitation with 16 bit math and integers.
A signed integer takes 8 bits and can take a value in the range from
-32,768 to 32,767. An unsigned integer is 8 bits and can take a value
in the range from 0 to 65,535. Okay, now that I've told you this, I've
experimented with increasing the values of my cluster and sector counts
past 65,535. Why? Well, if you have a drive with 2K clusters, one
paritition and it is 120 megabytes, then we can discern that there are
61,440 clusters in total. So what? Well, if my math relies on integers,
then we have exceeded the 32,767 cluster limit. So, I have tried to get
away from this. IF YOU GET ANY REALLY STRANGE ANSWERS AND YOU HAVE A BIG
PARTITION (over 120 MB), THEN YOU HAVE PROBABLY EXCEEDED THE MATH ABILITIES
THAT I HAVE IN THIS PROGRAM. If you could leave me a message on EXEC-PC,
AV-SYNC, Queued Access or Ye Olde postal servicee about what happened & how,
I'd appreciate it.
History:
10/13/91 Okay, the I have located the bug that caused
disks with over 32,767 clusters to go nuts. As some
of you know, this is the limit of a positive signed
integer in C and C++. By changing the variables to
unsigned integers and double long integers, the cluster
size limit is now 65,535 (with 2K clusters, this is just
shy of 128 meg). I'm having a bit of a problem with interfacing long
integers with the Interupt 21H 1CH function. If I can
get a true double long integer value, the program
will be set for any contingency.
9/29/91 Initial release.
I hope this program helps you evaluate some of your problems
or even makes some solutions/benefits clear. This program is SHAREWARE.
IT IS NOT PUBLIC DOMAIN. If you find that this program aids you, you are
required ethically and legally to register it after a 30 day evaluation period.
This software is priced at $5 for each concurrently used copy in an
organization.
Sincerely,
George Spafford
3001 LakeShore Drive, #329
St. Joseph, MI 49085
Data: (616) 468-5026 Queued Access BBS 19200-8-N-1
And now for the unpleasantries:
QDI IS DISTRIBUTED AS IS. THE AUTHOR (GEORGE SPAFFORD)
MAKES NO WARRANTY OF ANY KIND, EXPRESSED OR IMPLIED,
INCLUDING BUT NOT LIMITED TO TO WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE, WITH RESPECT TO THIS
SOFTWARE AND DOCUMENTATION. IN NO EVENT SHALL THE AUTHOR BE
LIABLE FOR ANY DAMAGES, INCLUDING LOST PROFITS, LOST SAVINGS,
OR ANY OTHER INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT
OF THE USE OF OR THE INABILITY TO USE THIS PROGRAM.
----------------------------------------------------------------
Other Products:
Cache Test Find out just how much your cache really
helps!
CutIt Parse streamed files by x number of bytes
and add a CR/LF at the end.
FLC Compare two file lists and generate a list
of duplicates and/or unique files.
PadIt Convert Variable length records to a Fixed
length format.
QHI Quick Hardware Identification. Identify your
processor, its approximate speed, serial ports,
parallel ports, game ports and so forth.
ZipCodeTool Look up zip codes by state or city. If you
know the zip code, you can look up the city
and state.
ZipWhen Insure that the Zip file's date matches the
date of the newest file it contains. This
reverses the annoying time stamping that some
BBS packages do.
-- EOF --