These pages are dedicated to the Texas Instruments TI-99/4A home computer. They contain mainly technical information on the various processors and memory chips found in the console, on peripheral cards and cartridges and on additional hardware. Although the emphasis is on hardware, I included numerous examples of assembly language programs to demonstrate how to access hardware or illustrate undocumented features.
These pages are not for beginners! To follow the discussion you'll need some knowledge of digital electronics and notions of assembly language programming. I tried to adopt a fairly didactic style, but this is by no means a tutorial. Nevertherless, you'll find an assembly language primer, an introduction to GPL language, an explanatory page for digital TTL chips and tutorials on how to solder and how to open your console and PE-box.
These pages are meant to load fast over a phone line: no fancy graphics, no pictures inserted in the text and (God preserves us) no frames! In addition, the whole site is available for download as .zip files.
This site is currently hosted by the University of Geneva, Switzerland.
It used to be hosted by Stanford, then by the University of Sheffield, but this changed when I moved back to my hometown.
So if you've bookmarked the old site, please replace it with http://www.nouspikel.com/ti99/titechpages.htm
I hate to brag,but I must admit that it feels good to be recognized by
one's peers. So let it be known that this site was granted the Edgar Mauk
Award in the catagorie `TI Websites`, at the European TI-Treffen in Gent
(Belgium), on October 7th 2000. Click here
In 2003, it was granted the Jim Peterson Award in the category "Community
And in 2005, it was selected for the Rob Tempelmans Plat award, a joint initiative from the Chicago TI users group and the Dutch TI Gebruikersgroep to honor the best internet sites for the TI-99/4A community.
Below is the site map. Note that some pages may be listed under more than one header.
TMS9901 Programmable system interface
TIM9904 Four-phase clock generator and driver
TMS9918A (or TMS9928A or TMS9929A) Videoprocessor
TMS9919 Sound generator
TMS5220 Speech synthesizer
CRU (communication register unit)
Cassette tape interface
TTL chips featured in the schematics on this site
Adding a second RS232 card
Replacing card ROMs with EEPROMs
Installing the speech synthesizer inside the PE-box
Powering the joystick port
PC joysticks adapter
Overclocking the console
Supressing wait states
Jeff Brown's interrupt mod
Replacing the console ROMs with EEPROMs
Disabling the console GROMs
Console CRU interface
Assembly language primer
GPL: the GROM language (I) , Part II
The TI-Basic interpreter
Tips & tricks
Standard headers: writing DSRs and Calls
Calling GPL from assembly
Floating point numbers calculations
Using the internal timer *
Sound generation *
Speech synthesis *
Direct access to the disk drive controller *
Scanning the keyboard *
Keyboard challenge (+ tutorial)
* Part of another page
Writing DSRs for the USB-SM card , Part II: EEPROM loader
Known TI-99/4A bugs
This TI-99/4A Ring site is owned by Thierry Nouspikel
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