Comment by mrandish

There was also a beige version released later (http://www.mainbyte.com/ti99/computers/ti99beige.html). I have both variants in my collection and they're both attractive machines, especially by the standards of the early 80s. The best part of the design was that it had a decent keyboard (unlike its predecessor the TI-99/4, which is much more rare - and for good reason). It also was the first home computer to have hardware graphics support in the form of TI's home-grown TMS9918 VDP chip which outlived the computer it was made for by many years. It was used in dozens of different 8-bit computer models from manufacturers around the world and spawned several improved variants, including the graphics chip in the Sega Master System console!

Unfortunately, the 99/4a was brutally hobbled by some bizarre design choices that nerfed its performance including forcing the 16-bit CPU onto an 8-bit system bus which halted the CPU to spread each 16-bit read/write into two sequential operations. This was made worse by the fact the CPU used a memory-to-memory architecture (even for most of its own registers) and all the memory was behind that '8-bit wall' - except for 256 bytes of 'fast scratchpad' (aka just 'normal memory' on other 8-bits). Plus the GROM was on PROM chips that were even slower than RAM, introducing more latency.

The whole GROM thing could have been a nice idea if it weren't for the 8-bit bus and slow PROM chip speed. Unfortunately, TI execs were more interested in finding a home for excess PROM chip inventory than making their home computer the best it could be. So, it was hard to extract high-performance game graphics from the system, requiring significant ingenuity from developers.