View Full Version : TI-99/4a.

October 20th, 2009, 06:36 PM
No topic on the TI-99 in a forum about Texas Instruments computers? Well, I'm changing that.

I got one of these awesome things today for $10, with a weird mismatched keyboard that looks like it came from a beige model, while it's a black and silver model. Works perfectly, but I only have one game, The Attack, and I can't find my controller for it. :(

The keyboard is a little yellowed, so I might have a great Retrobright experiment here, if I can remove the keys.

October 20th, 2009, 08:27 PM
Do you mean your keyboard looks like this;


You could have ended up with one like this;


Short story on how these TI machines turned out this way (if you're interested :)

I had a couple excellent condition silver units but I also wanted the 'cheaper' beige unit. I finally got a hold of one, and wouldn't you know - it was a dud. Well, I pulled the MB from an extra silver and stuffed it in the beige. Trouble was, on that one the keyboard didn't work - so I switched the keyboards and this is what I ended up with. Besides these two, I have acquired 2 more working silvers. I now have 3 working silver machines and 1 working beige with a silver keyboard and a non working silver with a beige keyboard. I'm even starting to confuse myself . . .

Give a post on how you make out removing the keys. If they come off easily for you, I'd like to know. I may switch my keys around so my beige unit has the rightful key tops.

October 21st, 2009, 09:34 AM
Well, my plan in popping off the keys isn't to replace them with different keycaps, it's just to clean them. I've never seen something so yellowed as these keys. Mine looks like the one on the top.

As for removing them, I just took a flathead screwdriver and used it as a lever to pop the keys off. Due to the odd key arrangement on the TI-99, some keys are packed in tight and some work will be required to get them off. Start with the corner pieces and work your way in.

Going even more advanced on your story, I heard that TI dumped their spare keyboards, among other parts into Radioshack and similar stores when they left the computer business. There were apparently so many of them that some stores didn't run out until the mid 90's and some stores might have them in the way back still.

October 21st, 2009, 12:58 PM
Yes I understand you were removing the keys just for de-yellowing purposes.
Ok then, I'll give my beige keys the prybar and hopefully I won't ruin any. Thanks for your info.
My beige unit has no yellowing, even the keys are still nicely beiged :)
If my TI Beige unit's picture appears more yellow than beige it is strictly due to the incandescent lamp that sits next to me on my computer table. When I got my one and only Beige TI I was thrilled with it's 'looks like brand new condition'.

FIY, or anyone's - the MB from the Silver fits right into the Beige case. Notice that the on/off switch on the Silver unit is on the front, but on the top with the Beige unit - you'd think that would be a problem - but it all works just fine due to a small plastic slider thing for the switch.


Note though that I am placing a Silver MB into a Beige case.
If you were placing a Beige MB into a Silver case, you wouldn't have the red 'on' LED OR the little plastic adapters for the switch. Incidentally the red on LED isn't a problem either. I just bent it out of the way inside the Beige case.

October 23rd, 2009, 02:31 PM
You are right about TI selling a lot of surplus components to Radio Shack. They started showing up as parts for the hobby crowd near the end of 1984, and were available for a couple of years. I have several of the keyboards and of the console power supplies in Radio Shack bags.

One very important note about the black keyboards: they are not all of the same type. There are actually four or five different variants, most easily determined by removing the keytops. Some of them have the same keytop type as the cream keyboards, but most of them have a set of contact fingers that are opened and closed by the keytop--these are actually the best TI keyboards, because you can remove the top and clean the mechanism to restore function when they start to skip or double trip.

All motherboards fit in the various cases--and there are a couple of minor variations on the black-and-silver case too, but those are all related to the solid state software label at the cartridge port--it is missing on later ones, as seen in the picture already posted here. The power switch on the cream model is in the same area it would have been otherwise. Note here: the reason for the label being there dates back to the TI-99/4. Some versions of the 99/4 had an internal speaker located below the grille above the cartridge slot. The volume control was a slide switch that ran the entire distance between the sides of the cartridge slot depression right at the front. I have one 99/4 with this configuration and one with the same configuration as a 99/4A with the slot covered and no speaker.

If you need 99/4A information, there is a wealth of data at ftp:\\whtech.com

October 23rd, 2009, 09:08 PM
Okay, my power supply for the TI-99/4a makes a buzzing noise when it's plugged in. Should I be concerned or not? It also makes numerous suggestions not to join the secondary wires, does that mean I shouldn't let the two wires that come out of the transformer cross?

Also, is there any place where I can buy a converter to use an Atari joystick? I've seen diagrams that show you how to make it, but I'm not sure where to find DB-9 connectors.

October 24th, 2009, 12:57 PM
Many of the power supplies make a buzzing noise. That is generally not a major issue, but you can usually get one on Ebay if you want a spare. The Atari joystick adapters are also readily available there. I've seen three or four of them sold over the last month or so.

There is a great set of instructions for making your own on this site:


Just go to the projects/upgrades section. . .but all of the information on his site is good.

You can always buy a bunch of the connectors on Ebay as well--look around carefully and you will find lots of them for not too much money. Radio Shack still stocks them in their electronics parts bins as well, if you just want one or two for a somewhat higher price. . .