80-Bus News


May–June 1984 · Volume 3 · Issue 3

Page 41 of 51


A serial daughter board for the GM816 (see above) providing two 8250 UARTs with RS232 interfaces. These UARTs have programmable baud rates, stop bits, parity, stop bits etc, and also spare user-programmable input and output bits.


80-BUS Speech board, using the National Semiconductor Digitalker chip set. This card has a limited on-board vocabulary contained in ROM, and making it say anything outside of this limited library is extremely difficult. Produced by Arfon Microelectronics, who unfortunately went into receivership. Boards MAY still be available from one or two dealers.


Light pen, suitable for use with the GM812, GM832 and GM837 boards. Again, as AM819, this was an Arfon product, and so unfortunately it may prove impossible to obtain any more.


Original 59 key parallel interface keyboard from Gemini for use with the GM812/​GM832 video boards. Although only 59 physical keys, all 128 possible 7-bit ASCII codes can be generated. Discontinued (see 827 and 852).


A small board containing a Nat. Semi. 58174 Real Time Clock chip with battery back-up. Connected to the system via a Z80 PIO. Only available in kit form.


Special version of the Gemini GM827 keyboard for the Danish market. Replaced by GM852 low profile version.


80-BUS A/D convertor board. Originally produced by IO Research, but later taken over by Gemini. This board provides 8 channels, each of 8 bit resolution. Input range is 0 – 5 volts with over-voltage protection. Conversion time is approx. 30uS, including sample and hold phase. Support for vectored interupts, and on-board prototyping area.


A single/​twin 5.25″ disk drive unit using one or two Micropolis drives and GM804 PSU. For use with GM809/​GM829. Available in single and double sided 96tpi versions. Capacity in double density mode is 400K single sided, 800K double sided (formatted).


80-BUS CMOS RAM board from Microcode Processes. Contains 32K of battery-backed static RAM to give 1000 hours of memory retention during power-down periods. Flexible address decoding and Page Mode operation, but does not support Extended Addressing.


Gemini’s 87 key keyboard (parallel interface) for use with the GM812/​GM832 video boards. The keyboard has a 57 key main cluster, plus 11 function keys, 4 cursor keys, and 15 key numeric pad. Theses latter 30 keys may ALL be user-defined (via the GM812 or GM832 video boards) in both their normal and shifted modes. Replaced by GM852 low profile versions.

Page 41 of 51