False Mem Reset

[anduril66]

I tried the Fake Mem Reset prog by David L. Good, but can I request a customized version (for personal use), with some of the following features:
1)When you call the program, it shows the Mem reset message immediately w/o the starting menu.
2)ROM version 1.14 instead of 1.12
3)Exit with any keypress.
Many thanks.

[NETWizz]

I am already on it.

I can fix it so it says 1.14, but I cannot do much else to it without the source.

[NETWizz]

Okay,

Download this, unzip it, and send it to your calculator.


Then Asm(prgmMODIFY

What it will do is edit ZCLEAR to make it display 1.14

How it works.

It finds the location of ZCLEAR, calculates the position of 2 in 1.12, and then increases it by one.

So, if you run it once, it will return 1.13
if you run it again ZCLEAR will print 1.14
...
It shoud be good to 1.19

So, if you upgrade your calc os, just run Asm(prgmMODIFY until ZCLEAR returns the number you want.

It will not ever go to 1.20 instead, it will find the next ascii character, so if you did it enough, you could have it dispplay A which is 41h...

If ZCLEAR is not present, this program will exit causing no harm.

If you have a program called ZCLEAR that was not written by David L, it will screw up the program.

It uses write back to work.

[Adm.Wiggin]

whoa, thats awesome! i think thats cool how you can do that Jbirk! maybe, since David is back (), you could get the source from him

[NETWizz]

Here is the source, Adm.Wiggin.

It is really simple to do what I did.

[Adm.Wiggin]

cool... so that really just takes the $9F th byte of the program and changes it? wow...

[NETWizz]

No

It finds the program DE points to the data/size

Then it adds $A1 to the address and the byte is at the address.

Then it reads and writes to that area of ram.

ld hl,de is de+hl->hl

[Adm.Wiggin]

yes, so you add 2 to the program location, then you must add the offset for the byte you wish to change

[anduril66]

Is there a way to make a program hide or delete itself (without crashinhg the calc) after completing a task?

[David]

Huh, Jbirk wrote a patcher for ZCLEAR
Anyways, point 1 and 3 will be easy to fix. Point #2 (correct rom version), is also rather easy. I have considered using the TI-OS system routine for retrieving the basecode version, thus making it more realistic.

Anduril, yes, it's possible make a program hide/delete itself. It's just to do it the normal way. It might sound dangerous to delete a program while it's running, but nothing will strange will happen, providing you run it from TI-OS, running from a shell won't work thought, because it will try to write back to a program that doesn't exist any longer . TI-OS doesn't perform any writeback, it just deletes the program copy and doesn't care about whether the original program exists or not.

[NETWizz]

#include "ti83plus.inc"

.org $userMem-2
.db $BB,$6D

ld hl,modify
rst 20h
bcall(_chkfindsym)
ret c

ld hl,$A1
add hl,de

ld a,(hl)
inc a
ld (hl),a

ret

modify:
.db protprogobj,"ZCLEAR",0

.end


How this program works:

It loads the address containing the object type and zeroterminated name into hl, then rst20h copies this information to OP1. Next, bcall(_chkfindsym) looks up the information from the sym table (VAT); in other words, it finds the program.

After finding the program,
HL -> Sym Table Entry Object/Type byte (you could change this byte to protect/unprotect 5=unprotected 6=protected)
DE -> Size bytes (ther are two with the LSB first) inc de twice to get to the actual data in ram.
B = Flash page (if 0, in ram, else in archive)
C flag will be returned if the program is not found.

So, ret c exits if ZCLEAR is not found.

ld hl,$A1 ;loads hl with the number of bytes the program is in from the first size byte
add hl,de ;HL+DE->HL

HL now points to the 2 in 1.12

ld a,(hl) ;read from that mem address and store the 2 or whatever it is in A.
inc a ;A+1->A
ld (hl),a ;A-> value at memory address defined in HL; put simply, write the new value back.

ret ;Exit the program


Going the extra distance:

After the ret c, you should add something I think.

add this:

ld a,b ;flash page to accumulator
or a ;same as cp 0; are we on page 0, ram?
ret nz ;If not in ram, exit

Add that to prevent unpredicatle results if you have ZCLEAR archived.

[NETWizz]

[Adm.Wiggin]

you dont need the 0 if it is 8 chars... it cant be more

[anduril66]

Thank you very much.
Can you please compile the finished program and show me the source code (because I can't download programs rignt now).

It is very nice of you to do all this work for someone else.

[JoeImp]

How do you attach a file. I didnt believe you could.

Imp

[Adm.Wiggin]

you must be an admin to have that privelage set... it was set during the logo contest to upload logos...

[David]

[Adm.Wiggin]

thats cool David! you know too much about the TI-OS for me! ;)

wait, Jbirk taught me the theory behind that! you check what menu the user is in, if it is the memory delete, then check if they are on the clearing option, if they are, then you check for when they click it, then just display your screen... is that even close?

[David]

Yes, that's pretty close!
There are three bytes starting at (menucurrent) that holds the currently selected menu, sub-menu (eg math and stat menu) and item. So I just read from (menucurrent), and if it's 23h, then we're in the "Reset RAM?" menu

I will post the program here very soon.

[Adm.Wiggin]

sweet!!!!! you could post it under Downloads on unitedti.org... and make a news article that says something like "First Download added to UnitedTI.org!"