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INSTALL.DOC
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1988-01-19
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USING INSTALL/REMOVE Normally a TSR utility is loaded simply by
entering its name at the DOS prompt or as an entry in your
AUTOEXEC.BAT file. In order to be able to control the
loading/unloading of each TSR, you must run the INSTALL program before
each TSR (or group of TSRs) is loaded. That way, pertinent
information needed for removal can be intercepted and stored away.
The syntax for INSTALL is:
INSTALL [namelist]
where namelist is the name of the TSR utilities comprising the group
about to be loaded. The namelist parameter is an optional descriptor
containing up to 119 characters; it does not have to match the TSR
filenames. The descriptor is used in the list of installed utilities
presented when REMOVE is requested to perform a deinstallation.
The INSTALL utility should be thought of as a sort of
'bookmark' applied to the operating system. When INSTALL is invoked,
it records the current state of the system; Each time REMOVE is run,
it restores the system to the state it was in just before the last
INSTALL. Any TSR's loaded since the last INSTALL are disabled. Up
to 32 system states can be docketed. If you want the ability to
delete TSR's individually, you must run INSTALL before loading each
TSR. At the other extreme, you could run INSTALL only once, right
after the system power-up, then load all the resident utilities your
system can hold. Then a single call to REMOVE would purge them all.
The following sequence (which might be included in an
AUTOEXEC.BAT file) installs four resident programs. TIMEKEY and
FREEZE, a pair of utilities that appeared in PC Magazine's own
Programming/Utilities column, are each preceded by INSTALL, so they
can be deleted one at a time. SuperKey and SideKick, the venerable
Borland utilities, are loaded consecutively so that they will be
erased as a group:
INSTALL TIMEKEY
TIMEKEY
INSTALL FREEZE
FREEZE
INSTALL SUPERKEY SIDEKICK
KEY
SK
Eliminating the last TSR or group of TSR's is as simple as running
REMOVE. REMOVE displays a list of utilities currently installed (by
echoing the descriptive names you typed in on INSTALL's command line)
and prompts you to verify by pressing the Enter key. If the four
utilities had been installed as shown above, running REMOVE would
produce the following display:
Number of installations: 3
TIMEKEY
FREEZE
SUPERKEY SIDEKICK
Press ENTER to remove, ESC to abort
If you press the Enter key, the last group, SuperKey and SideKick,
will be released from memory. Pressing the Esc key simply terminates
the deinstallation harmlessly. Successive utilities may be deleted
through successive calls to REMOVE. Running REMOVE a second time in
the example above would show only two installations recorded, with
FREEZE the topmost TSR queued to be deleted next.
It's perfectly legitimate to load more TSR's than was
indicated in the namelist parameter. REMOVE will still delete
everything entered since the last INSTALL. REMOVE's list of installed
utilities, however, only reflects those designated on INSTALL's
command line. If you choose, you can even leave the command line
empty. It's usually convenient, however, to have an accurate list of
TSR's presented every time you run REMOVE.
INSTALL is itself a short memory-resident utility. Every time
it's called it consumes about 1600 bytes of memory, but, more
importantly, it inserts a resident "wedge" in memory that contains a
complete copy of the PC's interrupt vector table. A utility not
preceded somwehere in memory by one of these wedges cannot be
removed. REMOVE recovers both the the memory used by the programs it
unloads and the memory dedicated to their identifying wedge.
INSTALL answers the command to load additional groups beyond
the limit of 32 with the message "No room for more." Likewise, when
REMOVE is executed with no TSR's installed, it responds with the
warning "None installed." Resident programs can be freely INSTALLed
and REMOVEd as many times as you wish. In addition, there's no limit
to the number of TSR's you can place in a group.
Note that programs (or groups of programs) can only be deleted
in the reverse order in which they were installed. The removal of an
intermediate one would create all sorts of problems, one of which
would be the tricky proposition of moving all resident routines above
it down in memory to fill the hole, rerouting all appropriate
interrupt vectors to the modified addresses, and altering any
references to absolute addresses. Unfortunately, that's next to
impossible. If you have to purge a set other than the one most
recently loaded, run REMOVE as many times as necessary to regress to
the one targeted, then reinstall the ones above it.
It's also legal to run REMOVE immediately after INSTALL, with
no TSR's loaded in between. The wedge left by INSTALL will be
erased. In fact, although there's no obvious reason to do so, you
can run INSTALL several times in succession, then reverse the action
a layer at a time. You may also run other applications, if you
prefer, between the time INSTALL is invoked and a TSR is loaded.
In the unlikely event that you encounter a "Deinstallation
failed" warning in the course of removing a TSR, you should probably
reboot the system. It's possible you might encounter no adverse side
effects without the reset, but it's also possible that down the road
somewhere (and at the worst possible time) execution might skid to a
halt with a critical memory allocation error.