Keypass v3 by Samuel Stearley Copywrite 2000
Email: sstear70@calvin.edu
This file is best viewed with Wordpad
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Introduction:
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The benefit of this program is that unlike other password
programs you do not have turn the calc off with the program
to get the password protection.  Simply turn the calc off
normally with 2nd or diamond plus the on button.

Another benefit is that as the ti89 is only sort of suited for
typing, this program allows the user to input the password much
faster.

I believe someone made something similar to this for z-shell a
long while back.  And I was considering how one would make it
for the 89 and plans were running through my head and I knew that
if I did not implement this then those plans in my head would be
a distraction.  So here it is.





Installation:
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Send keypass to your calculator.  Then run it.  Do not run it
from a shell.  In the help line it will tell you to hold down
keys and then press on.  So hold down some keys and press on.
The protection will now be installed.  Now WHENEVER you turn
the calculator off, you must be holding those same keys down
when you turn the calc back on. If you do not hold down those
keys then the calc will turn off automatically.

For example if keypass is installed and you turn off the calc
while playing sma by pressing apps, then you have to be
holding down the correct keys when it is turned back on to
continue playing sma.





Uninstallation:
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Uninstallation now works, just execute keypass a second time.

If you can not remember which keys to hold down then turn on
the calc -but keep the on button held down- this way the calc
will remain on giving you the chance to pull out the batteries.





How It Works:
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At initiation tios loads a pointer to the turn off call into the
beginning of memmory.  Then to turn off the calc tios does Trap #4.
Trap #4 will execute code pointed to by the previously mentioned
pointer stored at the beginning of ram.

So I check if that pointer points to the OS, if it does then I
copy some code to ram, lock the handle so it does not move, and
overwrite the old trap 4 pointer with a pointer to my code in ram.
My code remembers the pointer to the old turn off function and
uses it to turn off the calc, then when the calc comes back on
it checks to see if the correct keys are being held down.

If it does not point to the OS then it assumes that KEY pass has
already been installed.  And it will then uninstall.

So far I do not believe that any other program uses its own code
to turn off the calc, so if a program can turn off the calc
deliberately with the use of trap4 or inadvertantly with apd then
the user will have to hold down the nessassary keys to turn the
calc back on.  The rom call which turns off the calc merely does
a trap4.





The fine print:
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I am not responsible for anything this program might do to the
 calc.  Or anything that might result from the use of this
 program.  And I do not guarantee that it works.
If you use a portion of the code in a program you write then
 please give me some credit.





History:
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v1-	-First release.

v2-	-Fixed uninstallation bug.
	-Renamed the program because the name was too similar to
	 the name of another password program.

v3-	-Added a signature for security reasons.  This was not needed
	 at all but I put it in anyway.
	-A french version thanks to Benz Christophe.  He also tested
	 the 92+ version for me.
	-Some optomization.