Shadow Microsystem 1982

Early Australian designed and built computer

Ariel designed and built an early Australian Micro Computer, the Shadow Micro Computer System, in 1980, with a second version, Mark II in 1982. Inspired by experience with PDP8 computer visualisation graphics, his first computer rig, an IMSAI, work with the Z80-based Galaxian video game board, and projects with Bush Video and other earlly Australian computer arts pioneers, he designed the Shadow Micro Computer System, one of Australia's first locally designed and built micro computers.

The Shadow was a multi board system with a Z80 microprocessor main board, and separate graphics, sound, interface, and other sub-boards mounted in a metal box approximately 35mm wide, 30mm deep, and 15mm high.

The Shadow was one of the best examples of a powerful and complete micro (or personal) computer design for the time, rivalling much of the functionality on offer locally and in the US, while still being competitive in price (it sold for around AUD $1,500 in 1985), depending on configuration.

The Shadow used many then leading-edge features such as surface-mount, wave soldered, printed circuit boards, originally with completely hand-drawn artwork, and double, triple, or quadruple 3.5 inch floppy drives.

Its sound board alone had four, 3 voice (and a noise generator) AY-3-8910 sound chips, and came with a Forrest Mozer- designed Digitalker speech synthesis chip set with a vocabulary of over 100 words. An additional 100 or so "non-legal" addresses in the chip's sound tables created unique and fantastic electronic sounds (some of which can be heard on the Rockmelon's album mentioned below).

It came with a simple word processor and graphics system, and with a dedicated internally developed graphics software package, Shadow Draw. The accompanying circuit diagrams are drawn on, and printed, from the Shadow using Shadow Draw (Mark II version).

The computer was manufactured and sold in small quantities, in one case as part of the computer printing company Bannergram (where the Shadow's graphic capabilities were used to print large posters and designs). It was also used as the computer for the Musikey computer musical system (computer-based MIDI composer and DAW controller) built by colleagues in 1987. Musikey sold 10 systems before the company unfortunately ran out of money, being unable to find local investors (wrongly seeing the US as a financial bridge too far).

Musikey took advantage of the Shadow's sound board and its Digitalker chip set in the last days of the pre-MIDI revolution (1982-1985 - where RS232 and similar protocols were used to comminicate between a computer and musical instruments) and added MIDI in 1986. The Australian band The Rockmelons assisted with the development of Musikey's features and used Musikey as a touring computer music device in 1987. Its Digitalker was used on the Rockmelons' 1988 album Tales of the City on the song Money Talks.

Note on images. Many of the older images in this collection are direct shots taken of monitors, some are taken by an original digital camera system designed and built by "Fat Jack" Jacobson (with unique aspect ratios), some are photos of printouts, and some from simple domestic 35m cameras of the day.

Shadow Microcomputer

(from the Shadow manual)

A Shadow Microsystem is an Australian designed and manufactured general purpose computer.

The system uses a multiple board design to allow for ease of expansion. By implementing a unique board stacking technique and a flexible 50-way bus connection system, the computer electronics does not require a mother board, card cage or card guides. The computer is based on a 4MHz Z80 to allow access to the large number of programs available for this processor.

The system supports powerful computer graphics based on an advanced VLSI CRT controller IC. This enables the production of medium resolution displays containing text, lines, arcs, circles, rectangles and patterned areas. Text can be printed in one of 16 character sizes using 256 user definable characters on a matrix of 32 rows of 80 columns.

The video display is a grid 512 by 256 pixels with up to 16 colours or grey levels per pixel. The colour output is mapped thru a colour RAM to allow any of the 16 colours being displayed to be selected from a palette of 512 colours.

The minimum system supports up to 64Kb of RAM and 64Kb of ROM, with provision for expansion by the addition of extra memory boards. The minimum system also has an extensive I/O, including an 8 bit parallel ASCII keyboard port, RS232C serial communications port, 8 bi-directional 8 bit parallel ports, and a Centronics parallel printer port.

Shadow Microsystem Boards

(Allowing the minimum system to be configured with additional functionality by adding boards)

    • Shadow CPU
      Shadow memory
      Shadow SoundIO
      Shadow Disk Adapter
      Shadow VGEN
      Shadow VRAM
    • Shadow VCR Interface
      Shadow Micro Switcher
      Shadow S100 Interface
      Memory Mother
      Memory Module

    System Hardware Specifications

    4MHz Z80 CPU
    DMA Controller for disk and video transfers to/from main memory.

    Main Memory:
    Up to 128 KB of ROM (with ROM type header to allow selection of 2716, 2732, 2764, or 27128 EPROMS).

    Mass storage:
    Disk controller with up to 4 single or double sided, double density Mini or Micro floppy disc drives.

    Graphics display controller with 1024 * 1024 * 1 bit mapped screen memory (128 KB of of video memory).
    Video zoom pre-scaler.
    Composite video output.
    Video expansion port.

    Serial I/O:
    4 x RS232 serial ports.
    Individual switch selectable Baud rates for each port from 300 to 31.25 KBaud.

    Parallel I/O:
    4 x 8 bit bi-directional parallel I/O ports.
    Can be used as two Centronics printer ports.

    Processor expansion port.

    Video Expansion Board Specs:
    Up to 4 planes of 1024 x 1024.
    Independent graphics display controller for each plane (no speed penalty for multiple planes).
    Master clock and video drives supplied by SBC to allow for synchronisation.
    Colour RAM to increase number of available colours.
    Video combiner stage to allow for overlay planes etc.
    Independent video zoom pre-scalers for each plane.
    RGB video output.
    Provision for a second expansion board (for a total of 512 simultaneously displayable colours).

Shadow Micro Systems Computer 1982

The Shadow Microcomputer System 1982

Shadow Micro Systems Computer 1982

Shadow System Box 1982

Shadow Micro Systems Panel

Shadow front panel

Shadow Micro Systems Circiut Boards

Shadow circuit boards

Shadow cicuit diagrams 1

Shadow circuit diagram, 1 of 10