Commodore High Speed Graphik Card for CBM 4000/8000 Series

Introduction

The Commodore High Speed Graphik (HSG) Card is a board that installs inside any Commodore PET/CBM 4000 or 8000 series computer. This board was developed at Commodore Braunschweig/Germany factory by Wilfried Rusniok (Hardware) and Dieter Preiss (Software, incl CAD stuff). Dieter was with Commodore from 1980 to 1990 and was involved in other projects like PC10/20, Sidecar, and the Amiga 2000.

There are two versions of this board using either a Thomson EF9365 (512x512 pixels) or EF9366 (512x256 pixels) Graphics Display Processor (GDP) chip. Both versions output in monochrome only. There are also rumours of a colour version but so far I have not seen it. The board contains 32K of dedicated RAM and does not use any normal PET/CBM memory for the screen. The onboard GDP chip is capable of plotting pixels, and drawing lines, as well as drawing and scaling text all on it's own at a speed of 1 million pixels per second. The onboard EPROM contains the firmware to interface to the board in 6502 assembly language. There is an additional EPROM that is installed in an OPTION ROM socket of the PET that adds a BASIC EXTENSION for this board.

A version of the HSG board is also available for the CBM-II series of machines in the form of a board in an external case with power supply and a ribbon cable that connects to a board which plugs into the CBM-II cartridge port.

Installation

The board connects to the main PET motherboard via the two expansion connectors at the back right. The PET video is fed to the board and then from the board goes into the PET monitor. There is a switch that allows you to select either PET video, Graphics, or software selectable. An additional connector on board allows connection of an external monitor to view the graphics mode. Two cables run to the main board to supply power. Lastly, one wire connects to the "M" point on the motherboard. The board contains an EPROM mapped to $A000 that is used as a library of routines. A second ROM is installed on the PET's option rom socket at $9000 and contains a BASIC extension. There is also provision on the board for a light-pen.

Operation

Make sure the selector switch is set to PET mode. To initialize the board you must type "SYS 40960". This will display the startup message on the PET text screen and patch the system to enable the BASIC extensions. You can then switch to software selected video mode. The display is now under software control.

Resources