What follows is a quick overview of Technosys and the Aamber Pegasus hardware...

The Aamber Pegasus hardware was designed in 1981 by the late Stewart J Holmes, and the software by Paul Gillingwater, The Pegasus is a simple design and displays text and graphics in black and white only, has no sound capabilities, but is based around the powerful (for its time) Motorola MC6809C CPU. An onboard crystal ran at 4 Mhz, but the actual CPU ran at 1/4th this speed. The basic system came with 4k RAM, and later versions had 64K RAM installed via an upgrade card. There was an optional multi EPROM board with a rotating dial that allowed you to select one of many different language environments and/or programs and games from six individual EPROM banks. One EPROM bank consisted of two 2532 EPROM sockets for a total of twelve sockets. One bank of two sockets were mapped to the $0000 and $1000 address space. EPROMs available include ‘Extended BASIC’, ‘PASCAL’, ‘Tiny BASIC’, ‘MAD’ (Micro Assembler/Disassembler) and ‘FORTH’, as well as games such as ‘Tanks’, ‘Invaders’ and ‘Galaxy War’. Other EPROMs included ‘Monitor’ (which contains the machine BIOS and has to be present for the system to function), and ‘Word’ (a word processing application). Cassette based programs included ‘Snakes’, ‘Star Trek’, ‘Hangman’ and ‘Character Generator’ to name just a few.

The Pegasus was marketed on the strength of its support for multiple computer languages and low price. Kit set versions and prebuilt systems were available for purchase. A network version of the Pegasus provided connectivity to a 6809-based server (SWTPC-6809). The Aamber Pegasus system (particularly the networking version) attempted to address the New Zealand Government's ‘computers in schools’ initiative, but never produced the hoped-for large orders. It is thought that Apple Computers introduction of the Apple II computer into the New Zealand market, and it’s subsequent heavy educational discounting was the final nail in the coffin for Technosys and the Aamber Pegasus computer. Total production numbers are unknown, but it is thought that less then a hundred units were ever sold.

One of the most unusual aspects of the machine is that to save the cost of a CRTC, the processor set up some bits on the 6821(PIA) to control the row being read out, then stepped through a series of NOPs so that the address lines of the CPU could act as a big counter. This counter drove the X address of the display RAM. On every row, the CPU updates the row number selected from the character ROM (and programmable character RAM) and every 16th row it increments the Y address of the display RAM. At the end of the screen the output is blanked, and the CPU gets to do some “real” work until the FIRQ pin is pulsed by the 50 Hz line from the power supply. Essentially the Pegasus used the mains frequency to trigger vertical sync. Because of this, the CPU is ~90% occupied as a counter, so in a non-real-time application you could disable the FIRQ (one bit in the 6809’s CC reg) and the Pegasus ran 10x faster – albeit with a blank screen. In this respect it was similar to the Sinclair ZX81 which used it’s ‘FAST’ mode in much the same way.

On the left side of the Pegasus motherboard you can see a small blob of putty. This putty is hiding a series of diodes that act as a simplistic 8-bit ID. This 8-bit ID will only allow EPROMs encoded with a corresponding ID to work in any individual machine. For example, an EPROM from a machine numbered 2569 will not work in another Pegasus with a different ID. To defeat the ID check you could either alter the circuit under the putty, hack the effected EPROM by inserting the correct code (see Rewire4k app), or hack the main Monitor BIOS and disable the check altogether.

As a testament to the beauty and simplicity of Aamber Pegasus, there is still some activity going on around this machine, including new software and hardware development.

We are always looking for new information, program dumps, and hardware to document, so If you have anything to share, please feel free to contact me here.

For those interested in trying out the Aamber Pegasus for themselves, it has been recently emulated in M.E.S.S (Multiple Emulator Super System). You can download the latest M.E.S.S build from here, and all the ROM images, and WAV files you need to run the Pegasus emulation are available from my FTP server.

Please check out the blog for regular updates...

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Introducing the 1981 Technosys Aamber Pegasus, a New Zealand classic.

When I was a young boy living in New Zealand, and around the time I owned my Sinclair ZX Spectrum,

I was given an Aamber Pegasus computer by my next door neighbor who was involved with Technosys before it bellied up. The Aamber Pegasus I had came in a fancy fake leather (actually cardboard) suitcase style enclosure, with the keyboard exposed at the front for easy access. Unfortunately, in the early 1990’s my parents, in a spree if tidying, threw it out while I was away studying at university...Ever since then I’ve always longed to get another Aamber Pegasus, and in late 2006 one was donated to me by Michael Fincham who rescued it from certain destruction. This Aamber Pegasus is ID 2569. A second Aamber Pegasus, ID 2856, was purchased in late 2009, and arrived heavily modified. Unlike the first Pegasus, this unit included the cardboard case, multi EPROM expander board, and some previously missing programs on EPROM.

Aamber Pegasus

If you can help with extending our library of documents and software, please contact me.

Over the last 6 years, and with the help of some dedicated enthusiasts, I have collected and archived much about this little known computer. On these pages you will find links for downloading many Aamber Pegasus documents, manuals, programs, and some general information too. At the top of this page you will see a navigation menu bar which will take you to all the major sections within this Aamber Pegasus web site. included in this menu is a link to an Aamber Pegasus blog which is regularly updated with news and information about software, hardware, archived manuals and any recent developments including many new programs.

RAM 4kB expandable up to 64kB

ROM Monitor + various other languages and games

Keyboard 62 key full stroke

Released 1981

Price Unknown


CPU 6809

Speed 1MHz

Video Monochrome

Graphics 32x16 characters - User definable graphics

Sound None