Development resources

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This original version of this page is located at the Atariage game programming subgroup.

This page gives an overview of resources that may be useful if you intend to write software for the TI-99/4A.

If you are the owner of one of the programs or sites and do not want it posted, please let me know and it will be removed immediately.
Also if you think a reference to an important development resource is missing, then please let me know and I'll be happy to add to the list.

Below is an overview of most of the development resources for the Texas Instruments TI-99/4A Home Computer:


Windows-based emulator including TI-99 ROMs under license from Texas Instruments
Debugger, memory heatmap, OS file support, support for 128K bank-switch carts, possibility to record AVI movie (no sound).
Status: Still under active development
Multiple system emulator that supports the TI-99/4, TI-99/4A, TI-99/8, and Geneve.
Emulates more than 400 systems. Requires ROMs from the original systems. Features debugger, most accurate emulation, support for 64K bank-switch carts, possibility to record AVI movie with sound.
Also see the MESS section in ninerpedia.
Status: Still under active development
Windows-based emulator of the TI-99/4a
Good TMS9900 cross-assembler included. No debugger.
Status: Updated version released in 2009
Windows based emulator with 80 column support
Status: Still under active development
Linux-based software simulation of the TI-99/4A
Status: Stalled
Commercial DOS-based emulator licensed by Texas Instruments to sell ROMs
Status: Stalled

Programming languages

Windows based TMS9900 cross assembler with GUI and ability to build 8K cartridge roms.
Is part of the Win994a emulator.
Status: Updated version released in 2009
TMS9900 cross assembler TIasm will build 8K console (>0000) or cartridge (>6000) rom.
Is part of the V9T9 emulator package. Source is included.
Status: Stalled

Programming libraries

Library in assembly language for programming Arcade Games.
Includes routines for handling tiles, sprites, sound & task scheduler. Documentation included.
Status: Still under active development
Library for using assembler-like language & routines from Extended Basic.
Great for putting more power in Extended Basic programs.
Demo Pong game and documentation included.
Status: Still under active development


1. Cartridge tools

Convert almost any E/A#5 program memory image to a GROM cartridge for emulation.
A version that will convert a E/A#5 program image to ROM cartridge is planned.
Note that you need 32K memory expansion for running the E/A#5 program stored in the cartridge image.
Status: Still under active development

2. File transfer

TI99 filemanager for windows. Great for transferring disk images to the TI-99/4A.
Status: Still under active development
The Windows software TI99-PC will read, write, format, catalog, copy and convert
TI-99/4A floppy disks on a PC. You will be able to transfer your real TI floppy disks
from/to the TI-99/4A.
Status: Still under active development

3. Sound and speech

Music tracker for the SN76489 sound chip running on Windows.
With the help of Tursi's ePSGMOD player you can play
the composed tunes on the TI-99/4A.
Status: Still under active development
QBOX Pro is the windows software that converts WAV files to LPC speech data for playback on the TI-99/4A speech synsthesizer.
This is a 16bit windows application but it still runs in Windows 2000/XP/Vista. It does require the BWCC.DLL library.
Status: Stalled

4. Graphics

This utility for Windows lets you convert graphics to text (programming language data statements) to be included
in your programs (basic, extended basic or assembler).
Supports double sized sprites. Includes code to demo character or sprite design. Includes 14 charactersets/examples to
work with. Has a built-in character editor, but still the idea is to work with your graphics in your favourite graphic
package (eg. Photoshop). Turn on an 8x8 grid in your graphic software to assist you.
This utility needs the .NET framework available for free at Microsoft.
Status: Still under active development

Tech manuals

  • Texas Instruments TI-99/4A user reference guide
The official user reference guide with details how to setup and connect your TI-99/4A.
Includes intrudction on the TI-BASIC programming language.
The official extended basic manual, explaining the 40 new or expanded commands, sprites, etc.
Online manual with command lookup functionality.
The official Editor/Assembler reference manual. Note that this is not a tutorial for beginners.
Still, it's an essential manual when writing assembler for the TI-99/4A.
The official programmer'a guide for the TMS9918A and its variants. The 9918A is the Video Display Processor
chip used in the TI-99/4A and several other home computers + game consoles of that era.
Description on how to write software that runs from cartridge ROM.
Details on "Monitor", the OS of the TI-99/4A. Disassembly of console ROM/GROMS and GPL interpreter.
Has details on interrupt routine, utility subprograms, basic interpreter, etc.

Tech tutorials

New tutorial on compiling a 32K bank-switched cartridge ROM image.
Video tutorial on file transfer from the TI to the PC using a serial connection cable.
Video tutorial on how to use QBOX Pro to convert a 8kHz mono WAV file to LPC speech data
for playback on the TI-99/4A with the speech synthesizer device. It shows how to embedd
the LPC byte stream into your own assembly language program.

Tech web sites

Introduction and basics of Texas Instruments TI-99/4A Home Computer.
Probably the best TI hardware and software tech page.
Very good tech site with many detailed pictures and reference area.
Includes various projects for upgrading your TI-99/4A, e.g. build a supercart cartridge.
Several hardware projects including pictures. Home of the 64K bank-switched cartridge project.
TI-99/4A Home Computer Book Archive

List groups

The above list groups are currently the main meeting point for the TI-99/4A community.
Search and you will find. Ask and you will get answers.
Registration is required for posting.
  • comp.sys.ti, covering all TI devices, including calculators


Provides a gallery of interesting games with images of the opening screen as well as an
in-play snapshot, along with a brief review tested on a real TI 99/4A system. Hardware
requirements are also listed. Has many good Extended Basic games.
WHTech is the primary archive - though it's a bit overwhelming.
But pretty much all software, hardware docs, etc, are available there.
It's undergoing a reorganization at the moment to hopefully make it more useful.
Site with useful file archive and forum functionality.

Other web resources

Here the focus is on programming games for the TI-99/4A
Has occasional topics related to the TI-99/4A