I provided the complete hardware and firmware design for this Heads Up Technologies avionics product in 1987. Among the things I provided were: schematic-diagrams for 3 circuit boards, 4.7K lines of firmware written in Intel 8051 assembly-language (3.6K in common with the "Gold" checklist), a large but unknown number of lines of MS-DOS support software written in C, 2 PLD designs (1 shared with the "Gold" checklist") and 90 pages of documentation for software-certification and other purposes.
The idea behind this product is that it provides audio briefings to aircraft passengers. Such briefings typically relate to the location of emergency exits, the use of seat belts and oxygen masks, and other safety-related topics, but can be have many other uses as well. In large airlines, flight attendants are available to deliver these briefings, but in regional (commuter) airlines or business aircraft, they are not. Hence, the need for an automated solution. The HUCAB was the first of a long line of such passenger-briefing products at Heads Up Technologies.
Though the HUCAB unit was largely superceded by the PBS-400 product long ago, as I write this (05/2001) it still enjoys some sales.