The UnArchive Command

UNARCHIVE.GIF

Command Summary

Moves a variable from the archive to RAM.

Command Syntax

UnArchive variable

Menu Location

Press:

  1. 2nd MEM to access the memory menu
  2. 6 to select UnArchive, or use arrows.

Calculator Compatibility

TI-83+/84+/SE

(not available on the regular TI-83)

Token Size

2 bytes

The UnArchive command moves a variable from the archive (also known as ROM) to RAM. A quick synopsis of the difference between the two:

  • Data in the archive cannot be accessed, but it's protected from RAM clears (which may occur during battery removal if not done carefully); also, the archive can hold much more data.
  • Data in RAM can be accessed for calculations, but it can also be deleted during a RAM clear or accidentally overwritten by another program.

It is, in general, not recommended to place real variables in the archive (since so many programs use them); also, some variables cannot be archived (see the Archive command for details). Although programs can be archived and unarchived, the Archive and UnArchive commands will not archive or unarchive programs from within a program. For the most part, lists are the only type of variable it makes sense to archive and unarchive in a program.

The UnArchive command doesn't do anything if the variable in question is already in RAM. However, there is no way to test if a variable is in RAM or archive, short of trying to access it and potentially getting an error.

Advanced Uses

The Archive and UnArchive commands can be used in conjunction for saving data as a program exits.

Optimization

The SetUpEditor command is often used in place of the UnArchive command when dealing with lists, for several reasons:

  • using SetUpEditor will not prevent the program from working on a TI-83, like UnArchive will
  • SetUpEditor will create a list with length 0 if it doesn't exist; UnArchive will throw an error
  • SetUpEditor saves space in the program, since it can unarchive more than one list at a time, and doesn't require the little L in front

Error Conditions

  • ERR:MEMORY is thrown if there isn't enough memory available in RAM for the variable.
  • ERR:VARIABLE is thrown when unarchiving a system variable or a application even if there is enough space.

Related Commands

See Also

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