SHOWPARK is yet another automatic hard disk parking routine. This program is
based on the AUTOPARK and TPARK1 program procedures. There are some
significant differences;

oshows hard disk statistics at beginning of program

oshows parked state in upper right of screen

orequest to DOS (versions 2 or 3) for interrupt vectors

oterminates and stays resident in a better fashion than INT 27H

oterminates and de-resides when SHOWPARK is types a second time

oreturns all memory to DOS when de-resides

oexits to DOS in a hard disk parked state (typing SHOWPARK twice is
equivalent to a conventional park)

oassumes only one hard disk- C:


SHOWPARK is intended to be more of an exercise in MASM assembly language
programming then a general utility. The source code is written using MACRO's
that can be transported to other applications. The procedures may also be of
general utility to the assembly language programmer. The source code is well
annotated and hopefully readable. The interrupt calls to DOS are those
currently prescribed for compatibility with multi-tasking environments and
MS-WINDOWS (Top-View).

The code demonstrates the use of interrupt vectors not defined by DOS for
communication to resident programs. The initial values of the interrupt
vectors are not defined in any texts that I have found. However, it seems
that FFFFH is found in the offset portion of these un-used vectors. (At
least in my system and a few others I've tried) This may not be a generality
but rather a feature of the operating systems I've tried. Here's how it is
used. If FFFFH is found in the offset portion of the vector for INT 80H,
SHOWPARK assigns this interrupt to a termination procedure then terminates
resident. INT 80H offset vector values other than FFFFH are taken to indicate
that SHOWPARK is already resident. If, when SHOWPARK is run, other offset
vector values are found, an INT 80H is issued and SHOWPARK terminates. The
interrupt to 80H will re-reside the former SHOWPARK, and the current
terminates without staying resident. Thus all memory formerly requested is
released.

Finally, several persons have commented on the fact that when a program
de-residing, DOS often does not recover all of the allocated memory. This is
due to the fact that the program prefix segment remains resident. This
program circumvents this problem by first releasing the prefix segment to
DOS, and then requesting memory to stay resident. Granted, it's a trick.
But it is one that works.

I hope that this program will be of use to assemble hackers that write
utility programs. Use this program source and it's use is free. The author
is not responsible for any problems that occur as a consequence of the use
of this software. You have the source code so you be the judge of it's
compatibility. Questions and/or comments are welcomed. Other free MASM
source code is desired by this author. If you have some nice stuff, please
pass it on.

Stephen Bialkowski
197 North 300 West
Smithfield, UT 84322
BITNET [email protected]
FIDO Logan, Utah