TI99/4a Notes

I recently picked up this Texas Instruments TI99/4a at the 2024 VCF show in Wall, NJ for about $65. I had picked up another TI99/4a at last years show also (2023) but unfortunately that machine did not work and it had a broken keyboard cable. So, I was hoping that I would have better luck with this one. My hope was that maybe I could use parts from both to make up one good machine.

It took me a while to get to testing it out. I also bought a couple of Commodore machines at this years show and I started with testing those machines first. Both of those machines worked - a Plus/4 and a VIC-20. So, that was exciting and I was now anticipating trying out this TI99/4a.

I had forgotten if the video cable I was using for the Commodores was also compatible with the TI99/4a. I had to do some reading to ensure that I didn’t screw anything up. As it turns out the cable is compatible and does not have any connection to the 12v pins on the TI99/4a port. Since I last tested my previous TI99/4a I have purchased a nice little LCD screen TV that has the composite video inputs on the standard three color RCA plugs, Yellow for video and White and Red for split audio. I used this TV for the two Commodore machines in the last few weeks and it works good. I do not currently have a working CRT monitor with a composite input so this TV is a suitable substitute for now.

I tried to double-check that the power brick that came with this machine was working. I used my multi-meter to check the voltages and it seemed to pass the test. So, my next step was to make sure the power switch on the front of the machine was off and I used a power strip with a switch to plug the power adapter into and then I plugged the 4-pin power connector from the power supply into the TI99/4a. I also plugged in the TV to the power strip and plugged in the three RCA ends of the video cable to the TV and plugged in the 5-pin DIN side of the video cable to the back left port on the TI99/4a. Finally, I flipped on the power strip and turned on the TV and tuned the TV to Input 1 and then I turned on the power switch on the front of the machine. It worked! The sign-on screen came on the TV. I hit the spacebar and then I was able to get into Basic and did the obligatory “Hello world” demo. It works! 

The last TI99/4a did show the red power light but was otherwise dead. So this is a big improvement. Hopefully it will stay on and keep working.

It looks like I got lucky and I won’t have to repair this machine. I tested all the keys and they all seem to be working. But I don’t have any cartridges or any other accessories at all (besides the included RF Modulator which I am not using). I decided to do some reading online and watch some videos before I decided how to proceed. I will need to figure out how to get some software.

After some reading I learned that the computer supports the same cassette players as I used on my Tandy or Commodore but I would need to get a cable to interface to the cassette port and it is not the same cables as I already have with those other machines. I also will need an adapter for the joystick ports. I can use my Atari joysticks but the joystick port is not standard and will need to be broken out into two Atari style ports. (One of my Atari joysticks works and the other one does not).

I looked at how I might get a cartridge or two, or maybe a cassette. After looking around and watching some video I realized it would probably be cheaper to use an adapter that uses SD cards that can load multiple pieces of software on one SD card instead of trying to buy several cartridges or cassettes. Ultimately I decided on either a FlashROM99 or a FinalGROM99. The FinalGROM99 is the latest iteration of the FlashROM99 so that made the most sense if I could find one. I read there were shortages and some sources were sold out and had a waiting list. I considered buying the older FlashROM99 which I found at one source but then I found a FinalGROM99 for a decent price at a source not far from me here in the US. Some of the other sources were overseas.

The FlashROM99 was available for about $35. The FinalGROM99 I ended up purchasing was twice that. But the earlier version did not support subdirectories on the SD card and thus was limited to 171 entries in the root of the drive. The FinalGROM99 supported subdirectories and larger SD drives and also some other TI99/4a features I don’t yet understand, such as “Groms” files. Anyway, I did end up purchasing the FlashGROM99 and while I waited for it to arrive I watched videos about the device and read the manual online at the creator’s github. 

While I was watching these videos about the TI99/4a I also ran across similar devices for the Commodore machines. I had previously had success creating actual diskettes on my Commodore machines using a device I also purchased at VCF this year, a “Zoom Floppy”, and my actual 1541 disk drive, which works fine. But now I was considering getting one of these flash ROM devices for my Commodores and using SD cards instead of the actual floppy diskettes.

Well, I ran across this device named “BackBit”. After looking into it I realized that I could have probably used the BackBit Pro device on my TI99/4a and did not need the FinalGROM99. Oh well, I already purchased the FinalGROM99 and it was on it’s way. But I will be buying the BackBit Pro for use with my Commodores and Tandy CoCo machines. (The BackBit Pro supports several machines all with the one device. You have to purchase adapters to fit your machines but they support most of the machines I have, including the TI99/4a).

The FinalGROM99 arrived by mail and it was time to test it out. So, the next thing I have to learn is how to actually get the software images on to a supported SD drive. I read in the online manual that I could use any regular SD drive and that SD drives that were 2GB or smaller are formatted with FAT16 and 4GB or larger are formatted with FAT32. I scrounged through my stash of SD drives and found a couple of 1GB drives. I chose one and copied everything that was on it over to a folder on my desktop Win11 machine. Then I used Windows to format it to the standard FAT16 then confirmed I could access it in Windows explorer. I now had a SD card ready to go. But how do I put TI99/4a software onto it? Where do I find the software and what format is it in?

I did some googling and found a couple of sources for software. I also watched a video where he said he downloaded software and just dropped it on his SD drive. But he wouldn’t divulge where he got it. It also took a little while to decipher some forum messages on AtariAge to learn where to find software. Apparently people hesitate to come right out and tell you where to download software since there may be some copyright issues. So, you kind of have to be patient and keep digging until you get the answer through clues left by others.

It turns out there is a big archive of TI99/4a software at a place called ftp.whtech.com. There is also a pre-made collection of software ready to drop on your SD card named “FinalGROM99.zip” buried in that archive. That’s the one I downloaded. Then I expanded it on the hard drive using Win11 and then I dropped all the files at once onto the SD Card. Then I Ejected the drive using Windows Explorer and then I removed the SD card from my Win11 box and brought it over to the TI99/4a. 

I did not get a case around my FinalGROM99 so I had to carefully tilt the machine back so I could see the slot behind the flip open door of the cartridge slot and carefully inserted the card into the slot. Then I made sure the power and video cables were in place, turned on the LCD TV, and carefully inserted the SD card until it “clicked” into its slot on the front of the FinalGROM99. Now I powered on the machine. It came on and I hit the spacebar to go to the next screen. To my delight the FinalGROM99 was on the list at number 2. I entered “2” and the FinalGROM menu came on screen and showed me the folders of the SD card. It works!

I used the , (comma) and . (period) keys to move from screen to screen. These keys also have the < and > which help us understand these keys as “back” and “forward”. After looking through some of the screens under the “Games” folder I chose one to try by entering it’s letter. The first game I tried was called Defender. Unfortunately it seems to require a joystick so I could not play it. I rebooted the device and chose another game, this time Ms. Pacman. I was able to play Ms. Packman using the S,D,E and X keys as my arrow keys. But I am not very good with those keys and the TI99/4a does not have a separate set of arrow keys like the PC keyboard. But it worked.

Before I explore more games I am going to wait until my joystick adapter arrives. In the meantime I would like to explore some non-game software that was available for the TI99/4a. I know that MultiPlan was available on cartridge and I imagine there must have been a few others. Hopefully a word processor or two. I would like to compare it to the Plus/4 as a potential personal office machine.

I would like to explore some cassette software. Maybe I can start up something from the SD and then save it out using the cassette port. I’m not sure how this will work but I am interested in finding out if this will be possible.

I also only have 16K of ram. So maybe I can explore a 32K expansion. I think maybe the BackBit Pro also works as a 32K expansion module. So, if I get the TI99/4a adapter then maybe that will end up being the best solution for ram expansion.

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07/01/24

I got the joystick adapter installed and tried out the two Atari joysticks I have. I again started up Defender and selected two player. The first player usd the smaller joystick that I had attached to the front connector. It worked fine. Then when I got to player 2 I switched to the large joystick I had connected to the rear connector of the adapter. It only worked to move to the right. I could not move left or up or down and I could not fire. I suspected the joystick was bad.

I browsed through the files on the SD card and found a diagnostic program. One of the choices was for the controller test. When I ran that test the first joystick (the smaller one) wrecked fine. But the second one (the larger one) did not pass the test. I did not try swapping the joysticks to the opposite ports to confirm, but I think that the larger joystick does not work. I will start looking for a second Atari joystick to replace it.