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Digital Group System

This system used a Z80 processor and a proprietary bus from The Digital Group, Inc. and came complete with dual cassette tape drives supporting a hierarchical directory structure, "Real World Interface" system which was housed in a separate box with about 8 different adapters such as A/D, D/A converters and a printer.

More on Digital Group

The earliest systems were available with a choice of processor Z80, 8080, 6800, and 6502 around 1975 and 1976. These systems had a simple tape operating system (I don't remember much about it), digital cassette drives (1 to 4) and a 32 char by 16 line display. Later, the system was only available with the Z80 since it was the most popular and easier to support only one. These later systems (around 1978 and 1979) had a 64X16 display, Oasis disk operating system, 8 inch floppies and a very large number of peripherals and other options. The systems were available in kit or assembled form which made them popular with many people. They were built in Denver, the company had around forty (?) employees, and went out of business in 1979.

A note from your curator: to my mind, this system has a nice solid design and metal case construction that harkens to DEC's PDP minicomputers. In a way, this is the "Mini of Micros".

Bryan Blackburn, master restorer of Digital Group systems

Bryan Blackburn is undertaking a total restoriation of a complete DG system, see our pages about that project and Bryan's visit and interview here at the DigiBarn!

Digitalgroup system at the DigiBarn

Rick Bourgeois, a DigiBarn virtual visitor sent us the following pictures
A Digital Group system operating "back in the day"

Rick Bourgeois writes:

Here are the details in the photo starting at the very top left with that wide thin box:
Phi deck - 4 independent phillips cassette based storage
tiny box is digital clock

Next row, left side with paper sticking out:
tdg dot matrix printer-parallel port interfaced
Dual 8 inch floppy disc
tdg 64 x 16 B&W monitor

Next row of 2 large identical boxes:
main consoles - the original tdg bus would not hold all of the boards they offered and still have
a large enough power supply so I split the system between 2 main boxes. One held 2 huge brute force power supplies and some audio boards for their votrax talking board and the other had 2 bus boards wired together to take the maximum 64K for static RAM and all the I/O,control and other option boards.  Ran amazingly glitch free.  They later came out with more compact and higher density dynamic RAM as well as more efficient switching power supplies. (It was very difficult to talk them into selling me just a second empty console box as they were always in short supply.)

Final bottom row:
tdg keyboard
dual joysticks

the contraption on the left with the manuals is a miniature MITE teletypewriter for impact printing and making "carbon copies"

The large terminal that sat just to the right as shown in the right hand photo was a Compucolor ISC 1500 color terminal that communicated serially with the system and rendered color pictures.  You can just make out a RWB American flag on the screen.  I actually used this terminal to display slow scan images that were acquired with the tdg Ham/RTTY board - way off to the left in the first photo you can see some transmitting equipment that I used for RTTY short wave communications.
All of this is now off the shelf appliance stuff but 30 years ago this was mind blowing technology!

tdg offered a huge library of really nice software as you can see from all of the manuals in both photos. One novel mod on this particular system was the ability to boot up from a number of different eproms into 6 or 7 different OP-systems from the CPM standard of the day to some really strange ones the tdg promoted.

Know anything special about Digital Group? Contact us!

See Also:

Our scan of the Digital Group bankruptcy auction notice (1979)

, an excellent site on all things DG!

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