UNIBOARD 6809 Single Board Computer

The UNIBOARD was designed by Compacta Inc. in the UK, but manufactured in the USA by Digital Research Computers of Texas (not the Digital Research Inc. in California that produced the CP/M operating system).

UNIBOARD features:

• 1 MHz 6809E processor
• 64KB DRAM (using 4116 chips, 56KB available for operating system and user programs)
• 2KB or 4KB EPROM
• 24x80 character video (6845) with programmable character generator (2716 EPROM)
• floppy disk controller (1793) for four 5¼" and four 8" single/double-density drives
• parallel ports (6522 VIA) for ASCII keyboard and Centronics compatible printer
• serial port (6551 ACIA) with 20 mA and RS-232
• two 16-bit timers (6522 VIA)
• 40-pin expansion connector with DMA (6844)
• optional -12V DC-DC converter
• 2-layer PCB, 11.0" x 11.5"
• the bare board (with 2 EPROMs and 2 PALs) cost U$99.95 (later reduced to U$49.95)
• a complete kit cost U$399.00 (later reduced to U$219.00)
• FLEX and OS-9 operating systems were available for it

This board had similar capabilities to the Z-80 based "Big Board" (also sold by Digital Research Computers of Texas). The keyboard port and video generator allowed building a very economical system. Using DMA for disk I/O avoided the need to mask interrupts during disk I/O, and allowed a 1 MHz processor to support double-density 8" drives. But it only had one serial port, and no battery-backed-up time-of-day clock. Apparently a hard disk drive adapter add-on was available, but I can't find any information on it.

The only information I could find at first was from ads and reviews in '68' Micro Journal:

• ad on p.54 in the August 1983 issue
• editor's review on pages 15-17 in the January 1985 issue
• hints for modifying and using, on page 47 in the September 1985 issue
• user review on pages 26-30 in the March 1986 issue
• another user review on pages 47-48 in the October 1986 issue

But in July 2019 I made contact with someone who had built a UNIBOARD years ago, and still has the board and documentation -- Rob Storey of Melbourne, Australia. He supplied me with photos of his board and scans of the documentation, and gave me permission to use them. He also created several videos of the board and his attempts to get it working again:

• forum message 1
• forum message 2
• forum message 3
• forum message 4
• video 1 - introduction
• video 2 - power up
• video 3 - reading PALs
• video 4 - repair attempts #1

In April 2020 another UNIBOARD owner contacted me. Less than a month later Matt was able to get his board reliably booting FLEX from 5¼" and 3½" floppy disks, using an external terminal connected to the serial port, as his keyboard and built-in video weren't completely functional yet:

• forum message 1
• forum message 2

In January 2022 Jeff E. sent me a copy of the original commented source code for the monitor ROM. I have added it to the ROM download file below. Thanks, Jeff!

(Click on a picture for a larger version.)

Pictures of top and bottom side of Rob's board (1.0-1.1MB .jpg).

	Compacta UNIBOARD manuals: Construction & Alignment, Errata, User's guide. (scanned images in 3 .pdf files, 77.7MB .zip)
	Compacta UNIBOARD schematics. (scanned image, 9.5MB .zip)
	Compacta UNIBOARD ROM images (monitor, character generator). (2 binary images, disassembly, original source code, 33KB .zip)

"FLEX" was a trademark of Technical System Consultants (TSC).
"OS-9" is a registered trademark of Microware LP.

Last revised 2024-Apr-04 12:34 PDT.
Copyright 2019- David C. Wiens.