TI-BASIC:Tokens

Each command, variable, and operation on the TI-83 series calculators is represented by a "token." This means that internally, the calculator does not store a command such as "cos(" as the letters c, o, s, and (. It stores a single number that it will later translate as "cos(" when necessary. In this case, the value is 196, but you most likely don't need to know that.

What you do need to know is that not all tokens are the same size. If there were 256 tokens or less, then you could fit all their values into 1 byte and be happy. Unfortunately, the TI-83 has more than 256 commands and variables. Therefore TI employed some trickery and made some tokens take up 1 byte (usually the most common ones, though they seem to have had a different idea of "common") and some take up 2 bytes.

What this means to you, as the programmer, is that the size of the program is determined by the number of commands, not the number of letters in it: a short line can take up more memory than a longer one if it uses a lot of commands. Furthermore, some commands will take up the memory of two commands rather than one, so a line with a few of these commands may take up as much memory as a line with more commands of the ordinary type.

Lowercase letters are the epitome of memory wasters: at a single character, they each take up 2 bytes of memory. A program that uses a lot of lowercase letters can fill up all of RAM very quickly! This may be avoided by using uppercase letters instead, which only take up 1 byte each. You can also save memory by replacing words such as "If", " or ", " and " with the appropriate commands, when displaying text. Such a command will only take up 1 byte, whereas the text may be much larger memory-wise. Lowercase letters are also not available on the original TI-83, so if you use them, your program will not work on it.

Token Tables

These token tables are unnecessary for TI-Basic programmers; they would most likely be of use for someone writing a TI-Basic program editor.

• One-byte tokens
• Two-byte user variable tokens
• Two-byte statistical variable tokens
• Two-byte window and finance variable tokens
• Two-byte graph format tokens
• Miscellaneous two-byte tokens
• TI-84+ only two-byte tokens

There are several ways to insert a token given its hex value; all of them require an assembly program of some form. One of the easiest is to create an assembly program using AsmPrgm followed by the hex codes you want to convert to tokens, assemble it using AsmComp(, and then unlock it (there are many programs that allow you to do this).