A Beginner’s Guide to the Texas Instruments TI-99/4A Computer



This is a guide for how to use an old computer platform that I have had an interest in for some time now.  I wrote a Game Opinion Summaries list for some TI99 carts something like a decade ago on this site, and I covered it in Console Opinion Summaries (I should continue that series sometime…). but while I haven’t done any more articles here about the TI99 other than thise, I have added to my collection for the system and used it a fair amount.  I even have a PEB now, as of last year!

To be clear though, when I say that this guide is a beginner’s guide, I mean beginner.  This guide is for basic operation of this old, late ’70s to early ’80s computer line from the well-known chipmaker Texas Instruments.  Anyone who knows how to use the TI99, as any longtime owner surely does, won’t get anything from this guide, but for anyone who just decided to buy one for some reason or who found one at a thrift store and bought it on a whim or something like that, perhaps this guide could be useful.

In this guide I will cover the design and ports on the computer, the basics of how to use its “operating system”, and cover how to use software via cartridge and cassette.  For more complex operation, such as with modern flash carts or for usage of the Peripheral Expansion System (PEB) or other such accessories, look for help elsewhere.  I might write a second guide someday if there is interest, but before getting to that point someone needs to know the basics, and that is what this is for.   There is definitely value here, I think — this system is not like a modern PC, there is a lot to learn for anyone who wants to use one without much background in early computers.


The TI-99/4A has two revisions.  The first is black and silver, and the second beige.  I strongly prefer the look of the first model, since its black and shiny silver look is pretty cool.  It’s a style which holds up well.  The second model, however, with its bland beige color, may be more in the emerging style of 1980s computers, but definitely looks much blander as far as I’m concerned.  Regardless, as far as function the two are mostly the same.  There is one revision of the second model which add a lockout to try to block third-party cartridges from working, though, which would be annoying.  A model one system will definitely avoid that issue.  So, I recommend a model one TI99/4A.  It was first released in 1981.

Regardless of the one you have, though, this computer is an enhanced version of the TI99/4, a rare computer released in 1979. TI99/4A systems are fairly common, but the first model is quite uncommon.  I have never seen one in person.  Some carts are compatible with the original /4 and also the 4A, while others only work with a 4A, and you can’t necessarily tell by looking at the cart which systems it works with though black carts apparently are usually also /4 compatible.  Also, while 4A systems are all the same in terms of design, only the case colors and a few details change, the /4 looks distinctly different from the 4A.  It has a chiclet keyboard instead of full-sized keys for instance.  Given how rare non-4A systems are, though, this difference barely matters.  You surely got a TI99/4A of some kind, and that is the correct decision.


These are the ports on a TI99/4A.  TI helpfully (hah) decided to not label any ports on the case, so while some are obvious, such as the power connection, others are not.  Looking at the computer from the front, where the keyboard is:

  • The controller port is on the left side.  This 9-pin jack connects to a cable with two controllers on it.  This 9-pin port was very widely used on older consoles, but DO NOT plug anything other than a TI99/4A joystick pair or an adapter for other systems to the TI99 into it!  Even though the port is physically the same shape as the controller ports on the Atari 2600, Sega Genesis or Master System, Colecovision, Intellivision, and more, TI used a completely proprietary controller format that unfortunately uses the same port.  The TI99/4A has two controllers on a single cord which plugs in to the port on the side of the computer.  Adapters to let other controller types work on the system will always have two controller ports, so you can attach two Atari-style joysticks to that one port.  Never plug any other controller in without an adapter, they are incompatible and will not work. In the worst case it could potentially damage something. Each controller has a digital joystick and a button, so they are very simple Atari 2600-style sticks.  They are not well liked, the stick and buttons are very mushy.  They are also known for failing too often, though mine all work.  A controller adapter for Atari 2600-compatible controllers is recommended if you get into the system more.  I have one that works with Atari 2600 and Sega Master System controllers.
  • On the back of the system are the video cable port, the power jack, and, next to the power jack, the cassette port. Each cable only goes in one way. The cassette port uses a 9-pin port identical to the controller port, but they are entirely different and each must go into its correct port.  A cassette cable has the 9-pin port one one side and three connections on the other side to attach to a tape recorder.  For power, several power supplies exist but they wall work the same.  I recommend trying to find one of the ones with the brick in the middle, as opposed to the brick on the plug; brick in the middle design is much more convenient!   It has a very long cord, which is nice.Please note that for video output, the TI99/4A natively supports either RF or composite video.  For RF you must use a proprietary TI99-only manual RF switch.  They work well but the resulting image quality will be lower.  The better built-in option is composite video.  The port here is called 5-pin DIN, and the TI99/4A uses the same composite video cable as the Commodore VIC-20.   The Commodore 64 can also use this cable, but it also has its own version with more pins.  Other systems’ DIN-based video cables may not be compatible though, so make sure you are using a TI99/Vic-20 video cable and not something else.  You don’t want to potentially break the machine by plugging something in that puts the wrong thing on the wrong pin.
  • On the right side is the accessory port. It has a sliding cover so you can hide the port when you aren’t using it.  This is where the speech synthesizer or other hardware addons connect. The speech synthesizer draws power from the system so it can be left attached to the computer. Other accessories, such as the PEB or a modern mini-PEB, do need their own power supplies in almost all cases.  You always attach the speech synthesizer first and then any other accessory unit second, through the port on the side of the speech synthesizer.  The speech synthesizer isn’t cheap anymore, but it is a very cool accessory I recommend getting.  If you do have a speech synthesizer you should probably buy the cartridge Terminal Emulator II, since it includes the best speech synthesis programming feature set that TI made for the system.
  • On top of the system, software cartridges go in flat on the right side. They only go in one way, with the label facing upwards.  TI cartridges generally stay nicely clean thanks to the spring-loaded covers over the cart’s pins, so they should work without cleaning the vast majority of the time. Please note that this side of the system will get warm as the power board is underneath this flat area.The other thing on top of the computer is, of course, its keyboard.  If you get a system with a working keyboard — and make sure that the keyboard works before buying, some TI99 keyboards are infamous for being failure-prone so get a good one — you will find that is works fine but is somewhat lacking in keys.  Anyone used to a PC or Mac keyboard will definitely have a learning curve here.  Deleting text is a multi-step process, for example.  Note where the arrow keys are and how to use them (with a modifier key).  Some modifier keys are done by holding Function and pressing a number key.  All TI99s came with a metallic strip showing what each button combo does that slides in to the slot above the numbers on the keyboard.  If you don’t have this strip it is important to make your own out of something, the computer really can’t be used without that key reference strip.  Software will expect you to know how to press PROC’D (Proceed), for example, and won’t tell you that this means that you need to hit 6 while holding down the Function key.The order is: 1:DEL 2:INS 3:ERASE 4:CLEAR 5:BEGIN 6:PROC’D 7:AID 8:REDO 9:BACK 0:(empty) =:QUIT.
  • On the front end of the system you will find the the power switch and, at least on a model one system, a red power LED light showing if the system is on.  The two models have different kinds of power switches but they work the same.

Using the Computer

1) Plug in the power, preferably to a surge protector.  If you have the brick-in-the-middle power supply as I recommend the power cord is quite long, which is nice, as is the transformer-in-the-middle design which saves outlet space.  The brick-on-the-end power supply will work just as well if you have space for it, though.

2) Plug in the video cable.  As I covered earlier, the options for this system are RF or composite, so you want to use composite.  Use a TI99/4A and/or Commodore VIC-20-compatible video cable and NOT any other cables; even if they look similar they may have an incompatible pinout.  The TI99/4A has mono audio, so there are only two leads on the other end of the cable.  Cables may be red and white or yellow and white.  When connecting the composite video cable, the red or yellow lead should go into the video port on your composite a/v input, and the white lead into the white audio port for mono audio. If you have the cables plugged in incorrectly, it will be obvious — you will get a loud buzzing noise instead of graphics.  The TI99/4A only supports mono sound, so a stereo cable is not available.   The red audio port on your TV or A/V switch will not be used by this system.

3) Make sure the controllers or cassette recorder are plugged in if you need them for the current game or program.  You can hot swap cartridges from the system menu, but it is best to have things attached before turning it on.  More on this below.

3a) If using a cassette recorder, remember that it needs separate power from its power cord and cannot draw power from the computer.  There are some cassette-only games that are loaded from Basic (see the software’s instructions for details), but many are modules for use within the Adventure or Tunnels of Doom cartridges.  If your cassette is a module for one of those two games, the game will prompt you for when to hit Play, Stop, or Rewind on the cassette recorder.  You can use just about any cassette recorder with this system which has Microphone and Audio In jacks, but it was designed for one called the Texas Instruments Program Recorder.  I have had issues with TI Program Recorders though, so while their color-coded plugs do make connecting each cable to the correct port easy, I don’t know that I would recommend them.  Newer cassette recorders may work better.  The Remote function will probably only work on TI players, but all that does is it doesn’t let you play, rewind, or fast forward the tape unless the computer is prompting you to do it, so it’s not all that necessary.  Cassette loading is very slow, it takes several minutes to load, but so long as the tape player is working correctly and the tape is good it works.

4) Put in the cartridge you wish to use now, if you wish.  Uniquely for a cartridge-based system, you actually CAN put TI99/4A carts into and out of the system while it is running, so long as you only do so from the boot screen and boot menu, before you hit 1, 2, or some other key to start a program.  It is safe to change cartridges from the boot screen while the system is on.  However, as with all classic cart-based formats, you should never remove a cartridge while the system is running the program on that cartridge as that could damage the system or cartridge.

5) Turn on the power.  The power switch is on the front right. If you have a model one system there is a red LED showing when the system is powered on.

6) After the bootup screen, a menu will appear.  Press number key 1 to boot into TI Basic (a programming language built in to the computer), or number 2 to boot the cartridge. Some cartridges have more than one program, such as various languages for Alpiner; the menu will tell you any other options.

7) Read the software manuals for any help understanding the games; some are simple and make sense on their own, but others require reading the manual to be understood.  This is NOT a system to just ignore the instructions on, many games will not make any sense without reading the instructions.  PDFs of many TI manuals can be found at http://pixelpedant.com/.  This website has many manuals but not every single one.  Oddly enough, http://www.AtariAge.com has the most active TI99/4A web forum.

7a) If the joystick is not working correctly, make sure that the Alpha Lock key is not pressed down into the lower position.  Alpha Lock is the only key on the keyboard which can lock into a lower position, and you will be switching its position frequently.  See below.

8) If you wish to quit out of a game back to the system boot screen without turning off the power, pressing Quit (the key combination Function and =) should usually exit back out to the system menu. Then you can remove the cart and put in whatever other game or program you wish to use.

Keyboard Basics


  • As I said earlier, look at the keyboard and examine where the keys are. While the alphabet keys are QWERTY, otherwise its layout is very different from a modern keyboard.  It may take a little time to get used to it somewhat odd and cramped layout.
  • As I just described above, the Alpha Lock key, in the lower left hand corner, is the only key which can lock into a lower position. This is your Caps Lock key, and it changes between lower and upper case.  Note that lower case is not actual lower case letters, but is instead just smaller versions of the upper case letters.  It’s important to get used to noticing the difference between the sizes.  I wish that it was actual lower case since that would be easier to tell apart, but this works.IMPORTANT: You will often want Alpha Lock pressed into the locked down position, for upper case, when in the Basic command prompt because file names and such must be in upper case.  However, when Alpha Lock is down the joystick will not read all four directions, so it must be in the upper unlocked position when playing a game with the joystick.  Yeah, you’ll need to click this key up or down depending on what you are doing.  I’ve gotten this part wrong quite a few times, heh…
  • Many keys have an additional symbol painted onto the fronts of the keys, facing you. The arrow keys, tilde, and more are there. You use these characters or functions by holding down the Function key, in the lower right hand corner of the keyboard, while pressing the key in question.
  • The Function key also unlocks the additional functions attached to the number keys, which are shown on the plastic strip in the slot along the top of the keyboard. You access these functions the same way, hold Function down while pressing the number in question. Note that unlike Alpha Lock this key does not lock down, you need to hold it. The strip above the numbers showing what the numbers do is removable because some more complex software changes the functions of these keys away from the default.  These programs would some with their own separate strip to put in there instead.  None of the regular games or such do this, so just keep the default one in all the time.  As I said earlier, if you do not have the official one create your own in the order I listed previously.
  • The Control key is not used in Basic or in most software. It is only for programs that use multiple sets of modifier keys.  Cartridge games generally do not do that.

Controlling the Games

Somewhat uniquely for its time, all TI99/4A games can be controlled with either the keyboard or a joystick.  While on most other computers of its day games either require keyboard or require joystick but only sometimes support both, on this system everything can be played with the keyboard.  Action games support the joysticks as well, but they are not required.  When playing on keyboard you use the four letter keys with the arrows on them to move and Enter usually as the action button.  As you would expect you don’t need to hold down Function to use the arrow keys in most of these titles, as you would in Basic, but it is those four keys.

Again, the joysticks come two to a cable, and each stick has a digital stick and a single button on it.  Most games seem to be one player only on this system, but you do get two controllers.  Since all games also work on keyboard it makes sense that the stick is digital.  The system does have a fairly expensive and rare addon which I do not have, the Milton-Bradley MBS, that has an analog controller usable in the few games designed for it, but otherwise the TI99/4A is designed for digital controls only.  This is fine for most games on the system but is worth mentioning.  There isn’t a mouse or trackball either.  Even so, games which support joystick will usually be a bit more fun with joystick than on the keyboard.  Choose whichever you prefer, though.

Saving Data

Most games and software on this system do not save. Most of of its games are endless score-attack games, so if you are interested in recording progress I strongly encourage you to either write down high scores on paper or in a notebook, or take pictures of scores on a camera, phone, or such.

The two most common carts that do save data are Adventure and Tunnels of Doom.  These two cartridges are not stand-alone games, but instead are carts that you must pair with a cassette, disk, or modern storage solution-based module which has the actual game data on it.  They must save data to external media since their save data requires much more data than any internal cartridge storage could have included back then.  Adventure modules, such as the cassette Pirate Adventure which was included in the box with Adventure when people bought it new back when it first released, are text adventures with fairly limited amounts of text.  Tunnels of Doom is an ambitious dungeon crawler RPG. Tunnels of Doom is one of the system’s most impressive games and is a must-play despite the setup hassle.

As I have described several times now, there are multiple ways to save data on a TI99/4A, including to a cassette, to a floppy disk with the PEB addon, to a modern SD card based PEB addon card, or to a modern small PEB replacement plug-in unit.  While newer solutions are better than the cassette method, they are also more costly.  I would recommend starting out with this system with a basic setup, and only getting into the more expensive modern options if you like it enough to want to keep spending money on the system.  Below I will describe the process for using a cassette, since that is the original, cheapest, and simplest form of data storage the system supports.

  • When using a cassette, if using the official cassette deck, attach all three cables from the TI tape cable to the color-coded connectors on the center left side of the cassette deck.  If connecting it to a third party player or a computer, the red cable on the TI cassette cable goes to your player’s Microphone port (this is used for saving data from the TI99 to the cassette), the white cable to the Speaker or Audio Out port (this is used for loading data from a cassette to the TI), and the smaller black plug to the Remote jack if your player has a compatible one.  You only need the speaker and microphone cables, remembering the color coding from the TI tape deck; the monitor jack is optional and is only for compatible players, it simply keeps the player from working when the computer doesn’t want it to. It’s the speaker cable, for loading data to the TI99/4A, and microphone cable, for saving data to your real or virtual cassette, that are required.  You can even connect a TI cassette cable to a computer or laptop’s speaker and microphone ports if you want to load and save to or from an audio file on your computer.  You may need to adjust audio volume settings to get it loading reliably, but this works.
  • When TI Basic or the game cartridge in question asks you “where is the database?”, to load from a cassette type in CS1 and hit Enter. It will then prompt you to rewind the tape to the point you wish to start loading from. Hit Enter once there.
  • Then, it will prompt you to hit Enter and press Play. If using the official TI tape deck, you can do these in either order, since thanks to the Monitor jack cable it won’t allow the tape to start playing at the wrong time. If using a computer or a different tape recorder, simply press Enter on the TI99 and then hit Play on the tape recorder or computer as soon as you can after that. The computer-data sounds of the cassette loading will play over your TV speakers while the game loads, which should take 200 seconds for most Tunnels of Doom or Adventure modules. Yes, that’s over three minutes.
  • Once loaded, it will prompt you to hit Stop on the cassette recorder. Do so. You are now done with the cassette recorder until you want to save. Saving repeats this process, just onto a blank tape or a tape with a save game on it you want to overwrite. Don’t overwrite the original cassette, of course!  That would erase the original program unless the tape has its write-protect switch on.

Additional info: Tunnels of Doom comes with two games on the cassette or disk that came packed with the cart when originally purchased, the very basic and combat-free Pennies and Prizes and the full game Quest of the King. Read the manual for more instructions on how to play Quest for the King, which is the main draw here.  You can also find many other fanmade Tunnels of Doom modules on the internet.

Additionally, for anyone interested in learning TI-99/4A programming, you can save Basic programs you write to a cassette or computer, if interested.  The system’s built-in TI Basic is fairly limited and can’t do much without addon cartridges that expand its feature set and speed up operation, such as Terminal Emulator II for speech synthesis or Extended Basic for more powerful programming, but it’s a start.


While the controllers have two on one cable, very few games for this system have multiplayer.  It’s unfortunate but true.  Some games do have two player alternating or simultaneous, but expect most games on this system to be for one person.

Conclusion: Why Get A TI99/4A?

The TI99/4A has a somewhat annoying to use keyboard, often-stiff-feeling digital-only controls, and a quite limited software library if you look only at its original cartridge-based releases.  So why is it so interesting, and why do I recommend that people do follow this guide and pick one up and start the TI99/4A journey?  I’m not entirely sure what it is, but something about this machine is interesting.  The games are often unique, for one; you won’t find anything quite like Chisholm Trail or Hunt the Wumpus elsewhere, and those games are well worth playing.  Tunnels of Doom is fantastic because, unlike most classic first-person RPGs of its day, it has a fully- featured in-game map so you can’t get lost.  This instantly makes it better than 99% of ’80s RPGs.  No TI99-exclusive title has ever had a legal re-release on any other platform, either, so if you want to legally play these games you need to own a TI99.  You can’t just buy a modern compilation, though it’d be fantastic if such a thing existed.

The system has an interesting story too, as I detailed in my Console Opinion Summaries review of it.  It’s both unfortunate that such an important and interesting platform failed, and entirely deserving that a company trying to lock out third parties from their computer, not console, platform failed in that effort.  The TI99/4A is a fascinating platform with more than enough reasons for someone to want to learn how to use one.  I hope that this guide is helpful for understanding the basics.

About Brian

Computer and video game lover
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