80-Bus News


April–June 1982, Volume 1, Issue 2

Page 51 of 55


V2 Gemini Micocomouters

GM 802 RAM Board

*64K Dynamic RAM *4MHz Operation *RAM Disable Function

The Gemini GM 802 is a Dynamic random access memory card with a capacity of 64K bytes, allowing the total memory capability of the Z80 to be implemented on a single card. The card utilises an active delay line to give full 4MHz operation with no wait states required.

The GM 802 also includes logic for a pagemode operation which, when used with the appropriate software, allows up to four memory cards to be fitted’ in a single system.

Additionally this RAM card supports the 80 BUS/ NASBUS RAMDIS signal. This allows the user to have ROM in the system, the RAMDIS signal ensuring that there is no bus contention with the 64K RAM.

GM 802 – 64K RAM B & T — £125 + VAT

GM 812 IVC Board *80 x 25 display format *160 x 75 pixel graphics

*On-board Z80A *light pen input *Programmable character *Flicker-free display generator

The GM 812 Intelligent Video Controller (IVC) board is an 8” x 8” 80-BUS/NASBUS compatible video display card. It features its own on-board Z80A processor to allow the video section of the computer to provide a variety of complex video functions without imposing any memory or processing overhead on the main CPU. Communication between the GM 812 and —the host system is through the bus via two Z80 1/O ports. All reading and writing to the display is transparent, providing a flicker free display. The standard screen format of the GM 182 is 80 x 25, which is the preferred format for most applications. The card also has an adjustable dot clock to provide alternative formats. The standard character set of 128 characters provides all upper and lower case alphanumerics plus additional characters. Lower case characters have true descenders. An additional 128 character shapes may be defined under software control. These can be used to provide inverse – characters or pixel graphics characters giving a resolution of 160 x 75. Additionally the user may define his own characters for special applications. The GM 812 includes both light pen and ASCII keyboard inputs. The light pen input can resolve a single character on the screen. The keyboard input provides a 32 character buffer to allow ‘type ahead’ without loss of characters. The GM 812 is ideally suited for use in either a AVAILABLE FROM Muitiboard system, or in a Nascom system running


GM 812 — IVC Board B & T — £125 + VAT

This is an OCR’d version of the scanned page and likely contains recognition errors.

Page 51 of 55