My first machine was a used TI-99/4A (beige case). It had 16K of volatile RAM that was shared with the video chip, no built-in storage (other than ROM cartridges), and an RF modulator for connecting to the TV. The included manuals had the pinouts of all the device ports, and I had to make a cable to be able to save data to a cassette tape. I also had to make an adapter cable so I could use a standard Atari joystick with it.
Eventually I got a speech synthesizer module at a garage sale that plugged into the expansion bus located on the side of the machine.
It ran its own dialect of BASIC that was a bit crippled, and it required a ROM cartridge to use “extended” BASIC to allow basic things like PEEK and POKE. I taught myself to program by typing in the programs in Compute! Magazine or from books at the library. Many times I had to port programs in books for other computers because there weren’t many written for the TI machines.