The Digital Group
Available:1975
Price:$375 minimum
Memory:2K RAM minimum
How many:about 3000
CPU:8080, 6800, 6502, or Z80
Display:composite video


Richard Bemis and Dr. Robert Suding founded The Digital Group computer company in 1974 to satisfy their computer ambitions.

At the time, Bemis ran The Digital Group Clearinghouse, a Denver-based newsletter for Mark-8 computer enthusiasts, and Suding was a self-taught Mark-8 "expert", who designed his own upgrades and improvements for the system, including a cassette drive interface and a boot PROM. Suding had one of the few working Mark-8 computers in the area, and like-minded hobbyists came from far and wide just to see his system and to get help for theirs.

Bemis was impressed with what Suding had accomplished, and convinced Suding that they should join forces and start a company, so Bemis, Suding, and their wives, incorporated The Digital Group to market and sell Suding's improved Mark-8 designs (2MB pdf). Bemis was to be the president, and Suding the resident genius and designer - they eventually sold about 300 Mark-8 kits.



Six months later in January 1975, the famous MITS Altair 8080 made its debut on the front cover of Popular Electronics magazine. No longer did the user have to assemble their system from scratch - here was a completed system with all of the parts included from a single source.

Bemis was convinced that The Digital Group had to get in on some of this action, so Suding created their new, reasonably priced, multiple-board computer system with these advanced features:
  • Intel 8080, Motorola 6800, or MOS 6500 CPU card
  • video display/cassette interface card
  • 8-bit parallel input/output ports
  • 2KB dynamic memory
    • The 3-board Intel or Motorola CPU kit cost $425, while the MOS 6500 CPU kit cost $375. Later, the Zilog Z-80 CPU was added to the selection for $475.

    The Digital Group didn't just copy the MITS Altair design as others did, they improved upon it, with features not available in other systems. For one, the DG system loads the Operating System from the cassette drive automatically with little user interaction. Additionally, the DG system was available with four different CPU cards - the rest of the system remains fully compatible, no matter what CPU card was installed. Technically, the DG system has three different buses for CPU, memory, and I/O. Because of this, the card slots are different sizes and dedicated to each card type:
    Card FunctionSocket Size
    Input/Output72 pins & 44 pins
    Video/cassette44 pins
    CPU processor100 pins
    RAM memory72 pins

    Assembling your system from a kit was no small matter - it could take more than a week of slow and careful soldering, assembly, and maybe troubleshooting, before you have a complete and working computer system. Just one memory board was estimated to take up to 5 hours of construction time, a three-board system was estimated by DG to take 2 days.

    As a small company selling kits and plans to hobbyists, The Digital Group had few employees, good cash flow, and were very profitable.

    Their early systems were just "stacks of boards", but by October 1976, The Digital Group introduced their "cover up" systems - their complete system could now be ordered with a heavy-duty case and anodized aluminum front panel, all in a DG-brown paint scheme. But this new 'professional' system is huge - weighing-in at around 40 pounds (20kg), and fully two feet wide (60cm).

    This is also when they changed their logo from the horrible blocky text to the round logo.



    In 1976 they had around 20 employees, by 1977 they had 60.
    Here is their price list and available components:
    Order CodeDescriptionKitAssembled
    "Bare" systems - includes IO-F, TVC-F, but no case or power supply
    8080-3BD3-board 8080 system w/ 2K RAM$425.00$645.00
    8080-4BD4-board 8080 system w/ 10K RAM625.00895.00
    6500-3BD3-board 6501/2 system w/ 2K RAM375.00595.00
    6500-4BD4-board 6501/2 system w/ 10K RAM575.00845.00
    6800-3BD3-board 6800 system w/ 2K RAM425.00645.00
    6800-4BD4-board 6800 system w/ 10K RAM625.00895.00
    Z80-3BD3-board Z-80 system w/ 2K RAM475.00695.00
    Z80-4BD4-board Z-80 system w/ 10K RAM675.00945.00
    "Complete" systems with case and power supply
    Z80-SYS14-board Z-80 system w/ 10K RAM$895.00$1,295.00
    Z80-SYS2Above w/ 18K RAM1,095.001,545.00
    Z80-SYS3Above with keyboard, monitor, cassette drive2,045.002,545.00
    Z80-SYS4Above with additional I/O, digital tape drive, printer2,675.003,225.00
    Miscellaneous
    IO-FComplete I/O board$65.00$95.00
    TVC-F512 character TV interface w/ cassette I/O130.00195.00
    TVC-64Full 64-character TV interface w/ cassette I/O140.00205.00
    GRAPH-6464 x 64 color graphics interface175.00225.00
    PHI-FDigital cassette storage I/O135.00195.00
    PHI-IDigital cassette drive-115.00
    CAS&CB44 digital cassette drive w/ cabinet480.00505.00
    PT96-COMP96-column printer595.00675.00
    MON-99-inch B/W monitor-175.00

    Floppy disk drive systems were introduced in October 1977:
    Order CodeDescriptionKitAssembled
    5-1/4-inch mini-disk subsystem in case
    DSM-COMP1Single drive$675.00$725.00
    DSM-COMP2Dual drive$995.00$1,145.00
    DSM-COMP3Three drives$1,495.00$1,695.00
    DSM-COMP4Four drives$1,820.00$2,045.00
    8-inch disk subsystem in case
    DSS-COMP1Single drive$895.00$995.00
    DSS-COMP2Dual drive$1,395.00$1,545.00
    DSS-COMP3Three drives (2 cabinets)$1,995.00$2,195.00
    DSS-COMP4Four drives (2 cabinets)$2,495.00$2,695.00
    "Complete" systems with external floppy drive
    Z80-SYS5Z80-SYS2 w/ DSS-COMP2$3,445.00$3,995.00
    Z80-SYS6Z80-SYS2 w/ DSS-COMP1, PHI-F$3,545.00$4,195.00
    Z80-SYS7Z80-SYS2 w/ DSS-COMP2, PHI-F$3,995.00$4,695.00



    They were growing fast - perhaps too fast - by 1978 they had over 100 employees. Quality suffered, systems were shipped late, and upwards of 80% of systems were returned due to manufacturing faults - expenses were exceeding income.

    They continued like this for a year or so, but could not correct or recover from the situation.

    In summer 1979 The Digital Group declared Chapter 11 bankruptcy. "We were inadequately financed," admits company president Richard Bemis.

    Related Links

  • retrotechnology.com
  • Selectric Typewriter Museum
  • Bryan's Old Computers
  • PC-History
  • Classic Tech
  • the real story - by Dr. Robert Suding
  • Dr. Robert Suding - call-sign W0LMD
  • BYTE magazine, Jan 1977




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