I worked in the Home Computer Division, developing the DSR for the Hexbus interface built into the TI 99/8 computer, and also did some maintenance of the code for the DSR for the external Hexbus Interface for the TI 99/A.
Both reached code complete and several initial "qual build" units were manufactured to test the production process. About 150 TI 99/8 systems were produced (with the Hexbus DSR in ROM) during this run. I'm not sure how many 99/4A Hexbus Interface units were produced.
Hexbus was released in the TI CC-40 computer and several Hexbus peripheral devices. Several more Hexbus devices were under development, including a 5.25" floppy drive, which also made it to "qual build" stage.
Internally, we used the heck out of all the released and unreleased Hexbus devices and systems, in an "eat your own dog food" approach.
In the Fall of 1983, as the IBM PCjr (aka "Peanut") announcement neared, and as home computer price wars raged, TI announced that it would be exiting the home computer business, and all production ceased.
The Hexbus-based TI 99/8, the Hexbus Interface for the TI 99/4A, the Hexbus Floppy Drive, and several other Hexbus peripherals were never officially released.