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Chapter 2: TI-83 Plus Specific Information 25

TI-83 Plus Developer Guide Third Release May 28, 2002

Token Based Data Types

This class of data types is made up of a size field and tokens that represent TI-83 Plus

functions, commands, programming instructions, variable names — essentially anything

that can be entered into an TI-83 Plus BASIC program.

TI-83 Plus Tokens

A token can be comprised of one or two bytes which represents system functions,

commands, and variables. Instead of having to store the entire spelling of a function

inside a program, the function can be stored as a token that uses only one or two bytes.

For most applications, the tokens are only necessary when using variables. This will be

explained in the section on Variable Naming.

A list of tokens and their values can be found in the include file, TI83plus.inc.

Program, Protected Program, Equation, New Equation, and

String Data Type Structures

All of these data types have the same storage structure — a two-byte size field, the

number of bytes for token storage (not the number of tokens), followed by the tokens

themselves. For example, if graph equation Y1 = LCM(X,5), it would be stored as:

Two-byte

token

Size byte LCM ( X , 5 )

07 00 BB 08 10 58 2B 35 11

Note: New Equation type should be treated like any other equation.

Screen Image Data Type Structure

There is only one data type for this class of data structures — the Pict data type.

This variable’s data is a bit image of a graphic screen minus the bottom row of pixels. It

is made up of a two-byte size field, which is always equal to 756d (2F4h) and followed

by the 756 bytes. The first byte represents the first eight pixels of the display’s top pixel

row. Each successive byte represents the next eight pixels. When the end of a row is

reached, the next byte is the first eight pixels of the following row.

Example:

size | First 12 bytes is the top row of pixels

F4 02 12 34 56 78 09 23 45 98 A3 CB DE 12

70 65 34 98 56 77 09 06 80 C5 4D 00

Second row of pixels

Texas Instruments TI-83-Plus User Manual

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