From WikiTI

TI hid a lot of secret key combinations in their OS/boot code, here is the complete list.

Alpha, S

Function: Calculator Self Test

Calculator Self Test When: Mode Screen

Mode Screen Provider: OS

This is the self test that's built into the OS. It's useful for checking the boot code version or sneakily clearing ram.

Even though this says it will "clear all memory" it doesn't even touch flash. TI doesn't realize that there is memory other than ram.

Here are the tests it runs:

Calculator ID: does your calculator have a serial number?

Crystal timers: HL is incremented for 1/256 second and displayed

USB power on: if a type A cable is attached, it sends power to it, though it doesn't even check if it worked

Each completed iteration of the follow two tests increases the on-screen counter OS checksum: this passes if when you add all the bytes in the OS together, it comes out to zero RAM test: this checks all 8 pages of ram for retention

LCD test: only you know if this failed

Keyboard test: checks each key individually to see if it works

ON + Clear

Function: Don't Parse Archive

Don't Parse Archive When: On Ram Clears

On Ram Clears Provider: OS

This combination tells the OS not to look in the archive for any user variables on boot. What this means is that any programs in the archive will not show up and port 23 will not be set correctly. This function is useful if you accidentally corrupt your archive and the calculator enters a boot loop. Be warned that since port 23 is not set up correctly, all apps will instantly crash.

ON + Left + Right

Function: Enable Press to Test

Enable Press to Test When: Turning calculator ON

Turning calculator ON Provider: OS >= 2.40

This is the menu that allows you to disable Apps and programs. The only way to undo it is to link with another calculator. Be warned that it will delete your groups for no reason.

This menu also disables all hooks. (Except USB and ONSCRPT/OFFSCPT)

ON + 5 + 8

Function: Delete all variables

Delete all variables When: Turning calculator ON

Turning calculator ON Provider: OS >= 2.40

This is part of Press to Test. It is almost exactly the same as the Reset Arc Both option in the memory menu except it won't delete:

PlySmlt2

Soumi

Svenska

This menu also disables all hooks. (Except USB and ONSCRPT/OFFSCPT)

ON + 2 + 8

Function: Delete all variables for Singapore

Delete all variables for Singapore When: Turning calculator ON

Turning calculator ON Provider: OS >= 2.40

This is just like the regular Press to Test delete except it has a slightly different white list:

CtlgHelp

Conics

Inequalz

PlySmlt2

Transfrm

This menu also disables all hooks. (Except USB and ONSCRPT/OFFSCPT)

Battery + Del

Function: Receive an OS

Receive an OS When: Inserting the final battery

Inserting the final battery Provider: Boot Code

This key sequence will tell the boot code to try to receive an OS. It will wait a minute or two, then give up. One very useful side effect of this is that it will clear all ram, making it an almost unstoppable way to reset your calculator.

Contrary to some people's beliefs, this does not delete your OS, it never has, it never will.

Battery + Stat

Function: Receive an OS via USB

Receive an OS via USB When: Inserting the final battery

Inserting the final battery Provider: Boot Code

This is almost exactly like ON + Del except that it will only try USB, it will ignore the link port.

Battery + Mode

Function: Boot code flash test

Boot code flash test When: Inserting the final battery with no OS installed

Inserting the final battery Provider: Boot Code

This is almost exactly like the regular OS self test except it has a final test which tests all of the flash memory. This means that it will erase everything in flash except the Certificate and the boot code. While that sounds scary, it's a nice way to format your calculator if you just want to start clean.