Texas Instruments HX-1000 Printer / Plotter

Texas Instruments designed in 1982 with the HEX-BUS a very innovative interface to connect intelligent peripherals like printers, modems or even a video interface to its new Compact Computer System CC-40 and planned to use it with the never released TI-99/8 home computer.

The physical interface of the HEX-BUS is a rather simple 8-pin connector and with peripherals having always two HEX_BUS ports, multiple peripherals can be connected in a daisy-chain mode. The Hardware of the HEX-BUS uses four Data-Signals [D0, D1, D2, D3], two Handshake-Signals [HSK], [BAV] and a common ground signal [GND]. The remaining line was reserved for future use and labeled [FUT]. With the drivers being "open collector", the interface allows bi-directional data communication, each Byte is transmitted in two 4-bit words in a Master/Slave protocol. Texas Instruments published not only the specifications of the HEX-BUS and the software requirements for peripherals, but even offered two different Intelligent Peripheral Bus Controllers (IBC), realized as ASICs (Application Specification Integrated Circuits):

Texas Instruments dropped out of the home computer market in March 1984 - after selling more than 2.5 million of the famous TI-99/4A - and production of the CC-40 was ceased immediately after. Consequently was the development of the HEX-BUS terminated and only a few of the already announced HEX-BUS peripherals were manufactured in significant quantities. Interesting fact to know: The TI-74 BASICALC and TI-95 PROCALC computers introduced in 1985 as successor of the CC-40 use a 10-pin Dock-Bus which is compatible to the HEX-BUS and added three signals: [RESET] and System Power Distribution In [PI] and Out [PO] to power peripherals from the computer or the computer from peripherals.

Texas Instruments announced or released during the short live of the Compact Computer 40 eight different products like printers, plotters and even a serial interface using the HEX-BUS Interface. Additional peripheral devices were planned or released from Third Party vendors but are not listed as of now in our overview:

Texas Instruments introduced with the HX-1000 Printer / Plotter an x-y plotter with four-color capability using 2¼" (57 mm) wide plain paper. In addition to x-y plotting, it can print up to 36 characters per line at a speed of up to 12 characters per second. It connects with the HEX-BUS Interface to the Compact Computer System CC-40 and other devices supporting the HEX-BUS specifications.

Dismantling this HX-1000 Printer / Plotter manufactured in January 1984 in Japan by an unknown OEM reveals an ALPS Micrographic Printer DPG 1302, with the following key specifications:

If you have additions to the above article please email: joerg@datamath.org.

© Joerg Woerner, October 25, 2019. No reprints without written permission.