Texas Instruments TI-83-Plus User Manual

Chapter 2: TI-83 Plus Specific Information 37
TI-83 Plus Developer Guide Third Release May 28, 2002
Some system routines will fail and may cause a lock-up condition if bad data is input
to them.
For more information see the Variable Data Structure section earlier in this chapter.
• If there is not enough free memory available to create a variable, a system memory
error is generated, and the system’s error context will take over execution.
This can be avoided in two ways.
– Use the routine MemChk to see if there is enough free memory available before
attempting to create the variable.
– Use an error exception handler to trap the memory error (if one is generated).
To use option one, the size of the Symbol Table entry and the data structure must
be computed by the application. Therefore, the easiest is option two.
See the Error Handlers section.
• When a variable is created, its data structure is not initialized. Only the two-byte
size field, if one is part of the structure, is initialized to the size the variable was
created at. For example, after creating a complex variable, the entire 18 bytes of the
data structure contain random values.
After creating a list with 23 elements, the first two bytes of the data structure are set
to the number of elements, 17h 00h, the number of elements in hex, with the LSB
followed by the MSB.
If created data structures are not initialized by applications before returning to
normal system operation, the potential for a lock-up condition is very high.
• Routines for creating variables:
Create0Equ CreateEqu CreatePair CreateStrng
CreateRList CreateCList CreateRMat
CreateReal CreateCplx CreatePict
CreateAppVar CreateProg CreateProtProg
– Inputs:
OP1 = variable name to create.
HL = Number of bytes, number of elements or a dimension for some.
See the System Routine Documentation for exact inputs for each routine.
– Outputs:
Possible memory error, see above.
OP4 = variable name created with its sign byte set to the correct data type
OP1 = random
DE = pointer to data structure
HL = pointer to Symbol Table entry

Texas Instruments TI-83-Plus Specifications

General

Display Type	LCD
Display Resolution	96 x 64 pixels
Power Source	4 AAA batteries
Programming Language	TI-BASIC, Z80 Assembly
Backup Power	CR1616 or CR1620 lithium battery
RAM	24 KB
Processor	Zilog Z80
Weight	7.4 oz (210 g) with batteries
Dimensions	7.3 x 3.5 x 0.9 inches

Summary

Introduction

Conventions Used in this Guide

Defines conventions for program text, syntax, and optional parameters in guide examples.

Purpose of this Guide

Explains the types of programs that can be created and the guide's focus on Flash ROM apps and RAM assembly programs.

TI-83 Plus Specific Information

ARCHITECTURE

Describes the TI-83 Plus architecture composed of several layers: Hardware, Drivers, Tools, and Programming.

HARDWARE LAYER

Covers the Zilog Z80 CPU, RAM, and Flash ROM components of the TI-83 Plus unit.

Z80 RAM Structure

Explains the 32K RAM partitioning into areas like System RAM, User RAM, and Floating Point Stack.

Flash ROM Structure

Details the 512K Flash ROM composition, divided into 32 pages of 16K each.

System Routines

Explains accessing TI-83 Plus system routines using Z80 RST instruction and macro-instructions.

Variable Naming Conventions

Outlines rules for naming variables, including predefined and user-defined names and their formats.

System Variables Area

Describes preallocated system RAM variables essential for built-in functionality.

DRIVERS LAYER

Covers keyboard input, display access, and link port communication functionalities.

Display

Details accessing the TI-83 Plus display via system routines or directly writing to the display driver.

Graphing and Drawing — What’s the difference?

Differentiates between pixel-based drawing routines and graph routines tied to WINDOW settings.

TOOLS AND UTILITIES LAYER

Covers essential development tools like error handlers, utility routines, and debugging features.

Error Handlers

Explains setting up error exception handlers using AppOnErr and AppOffErr macros to capture system errors.

Temporary Variables

Discusses temporary variables used for intermediate results and their management.

Entering and Exiting an Application Properly

Details how applications interact with the TI-83 Plus application loader and state monitor.

Application Development Process

PROGRAMMING LAYER

Covers the final layer of TI-83 Plus architecture, focusing on TI BASIC, ASM, and Applications.

Applications

Defines applications as Flash ROM programs, their PC creation, signing requirements, and larger scale.

DEVELOPMENT SYSTEM

Introduces the simulator for general development, setup, and sample application creation.

Using the Simulator System — Requirements for Getting Started

Lists requirements for TI-83 Plus application development using Zilog Developer Studio and TI Simulator/Debugger.

Debugging the Application

Demonstrates setting breakpoints, modifying RAM, and using the Memory Map view for debugging.

Downloading the Application

Explains using TI GRAPH LINK or TI Connect to download applications to calculators.

Development Tools

DEVELOPMENT ARCHITECTURE

Outlines the TI development architecture based on the TI simulator/debugger and Zilog Developer Studio.

TI SOFTWARE SIMULATOR AND DEBUGGER

Describes the TI-83 Plus simulator for debugging applications, detailing menu options and operations.

Breakpoints

Explains setting and removing breakpoints via the manual setup dialog box in the debugger.

CPU View Window

Displays processor information such as index registers, stack pointer, and flags.

Flash View Window

Displays entire Flash memory contents, allowing address viewing and toggling between physical/logical modes.

RAM View Window

Displays entire RAM contents, allowing address viewing and toggling between physical/logical modes.

Key Press Recording and Playback

Allows recording and playing back key presses, with setup options for files and rates.

Support in Writing Applications

Lists resources for help in writing TI-83 Plus applications, including guides and tutorials.

Glossary

TI-83 Plus “Large” Character Fonts

TI83 Plus “Small” Character Fonts