In 1977, Dr Tom DeFanti, who had developed the GRASS programming language, was introduced to Jeff Frederiksen, a chip designer working at Dave Nutting Associates. Dave Nutting Associates had previously been contracted by Midway to create a standardised graphics driver chip that was intended for use in most of their future arcade games, as well as a the Bally Home Library Computer. Midway was interested in seeing the GRASS language running on their system, and contracted DeFanti to port it to the platform. A number of people at the Circle Graphics Habitat (today known as the Electronic Visualization Laboratory, or EVL) worked on the project, as well as some people from Dave Nutting Associates. The project at this point was referred to as the Z-Box.
Using this technology, Midway had planned to release a computer expansion module for Bally Home Library Computer a few months after its initial release. This expansion module was set to contain a keyboard, 2 cassette ports, 16KB of RAM and ROM, a serial port for printers/modems and an additional expansion port for other peripherals like disk drives. It would have come with the BASIC programming language. However, due to the production and shipping delays of the Bally Home Library Computer, the expansion module was put on hold. It was around this time that the name of the Bally Home Library Computer was changed to "Bally Professional Arcade" possibly due to uncertainty over whether the expansion module would ever be completed, hence the dropping of the name "Computer" from the name. The Bally Professional Arcade did, however, still receive a BASIC cartridge, which was considered the first expansion for the system. This was popular with programmers and computer enthusiasts despite the lack of the keyboard expansion module. It was around this time that the technology from the expansion module stemmed a separate project for a standalone workstation using Bally's chipset and the GRASS programming lanaguage, which ultimately became the UV-1.
The Z-Box coupled with GRASS3 (a version of GRASS programming language) was given the name of "ZGrass". When Astrovision took over the Bally home arcade division in 1981, it seemed the production of the computer expansion module was back on the table as the nameplates on early Astrovision units read "Bally/Computer System", prior to it ultimately being renamed "Astrocade ". At this point, the expansion module was called the ZGrass-32 and it was to come with the keyboard, 2 cassette ports and serial port initially planned, though by this time the memory had been upgraded to 32KB and it would run the GRASS programming language and be compatible the the CP/M operating system.
Further upgrades continued to be developed and announced. The "ZGrass-100" had the RAM expanded to 64KB and the disk drive controller and port added internally (5.25 inch floppy) This one was also believed to have a math co-processor (FPU), a 32K ROM containing the GRASS programming language, and compatibility with the CP/M operating system through the cassette / floppy disk I/O ports. The "ZGrass-1200" had the port changed to a "4 channel quad density" one. Finally came the "ZGrass-2000", which Astrovision had contracted Alternative Engineering Corp. to produce. Alternative Engineering Corp. had previously developed the Viper RAM expansion for the Astrocade, which also included a keyboard and ViperSoft BASIC, an expanded version of Bally's Expanded BASIC, hence it's likely they were chosen for this expertise. An order form was sent to those on the Arcadian mailing list who had previously shown an interest in the ZGrass expansion module. It was intended that the modules would be produced on an on-order basis. Customers could also order the ZGrass manual. However, by the time the ZGrass was production ready, the Astrocade was nearing the end of its life and suffering after the video game market crash that had just occurred. As a result, funding to produce the units could not be obtained and it was never released.
Only seven prototypes of the ZGrass computer expansion modules are known to have been produced for the purpose of displaying at trade shows. One was found up for auction on eBay in 1998. As noted above, the technology that started out in this project went on to become the Bally ZGrass UV-1, which was assembled by DataMax and subsequently renamed "Datamax UV-1", so all was not lost when the expansion module failed to reach the market.