pclogo2.gif (1638 bytes)





The Digital Group

One of the most original manufacturers of microcomputer equipment was the digital group of Denver (never to be confused with Digital Equipment Corp!) This group of hobbyists and designers, led by Dr. Robert Suding, could be considered more of a cult than a company because they adhered to a set of beliefs regarding computers and microprocessors that was generally at odds with the rest of the industry.

The Digital Group (or, as they preferred, "the digital group") believed that the industry would constantly develop new microprocessors and that the computer hobbyist should have a personal computer system that allowed him to change from one processor to another without losing the investment in the total system. They realized that the major part of the investment in computer equipment was spent on memory, interfaces, software, and peripherals. Therefore, they reasoned that if you purchase a CPU that quickly becomes obsolete (as they all do,) any investment in memory and peripherals specifically designed only for that CPU will be made totally obsolete. The digital group systems were designed to be independent of the manufacturer's chip design. Complete system compatibility was maintained at the CPU card level. All memory, I/O, and peripherals were completely independent of the CPU selected. They provided architectures from four CPU manufacturers: Zilog/ Mostek  Z-80, Inter 8080, Motorola 6800, and MOS Technology 6502.

With the digital group system, you could change from  a Z-80 to a 6800 by literally un-plugging the Z-80 board and plugging in a 6800 board. Once you had done so, all you had to do was power-up and read-in the 6800 operating system from a cassette, and you had a 6800 system. The same was true of the 6502 board. This was the basic idea behind the digital group designs, and it was very attractive, mainly to hobbyists.

In addition to the interchangeability of processors, the digital group system had quite a few other features that were far in advance of the other early microcomputers. It did not require a front panel with switches and lights since all the start-up software was contained in a ROM. It used a combination video and cassette interface board at a time when other computers still relied upon teletypes and provided a cassette-based operating system, which could use a standard unmodified cassette recorder to operate at 110 characters per second where other systems operated at 30 characters per second. It had a crystal-controlled interface that did not require constant adjustment and was extremely reliable. The video portion displayed 16 lines by 32 characters of a 7 by 9 character matrix and included math symbols, special symbols, and even the Greek alphabet.

The Digital Group system used reliable 8K static memory boards that would work with any of the CPU boards selected.

In addition, the Digital Group system was available to users as either a four-board system or any other sized system according to the owner's requirements. Since the system was designed for hobbyists, the highest level of interchangeability was provided.

Given all these advantages, the reader may wonder why the digital group was not more successful as a computer manufacturer. Well, they were completely hobbyist-oriented, and while they had dealers they never supplied equipment on a steady basis. You really had to want a Digital Group system very badly to put up with their erratic shipping habits. They only promised to ship orders in sequence received, and dealers had to wait in line with retail customers.

When a customer came into my store and asked for a Digital Group system, I would carefully explain the terms. The customer must completely pay for the system up front. I could not give a delivery date, and most likely the board kits would arrive in haphazard fashion with no order to the supply. It was almost impossible to get an assembled unit, so the customer must have the ability to solder complex printed-circuit boards. In addition, when the computer was completed it would still require complicated tests and adjustments requiring electronic test equipment. I did not have this equipment, but if the customer wanted I would send his assembled computer to my friends at the Personal Computer Company in Frazer, Pennsylvania, who specialized in Digital Group computers. They assembled these and installed them into a very attractive wooden cabinet which they called a "Personal Computer." As far as I know, they were the first to use this term for a microcomputer, way back in 1975 (not Apple as they often claim.) The reason for the wooden cabinet was partially that digital group did not sell any cabinets for a long time. When they finally designed some very attractive cabinets for their equipment, it was almost impossible get one delivered.

With all these negative situations, you may wonder why I bothered to become a dealer for this computer cult? (It could hardly be called a company.) Well, it was my principle that Computer Mart of New York would sell all available microcomputers. I also hoped that they would become more business-like. Besides, I did manage to sell most people who asked for digital group on something that would make them happier.

The demise of digital group happened quite a bit before the general disappearance of all 8-bit S-100 companies. There were just not many hobbyists who subscribed to the ideas of the group, and when the pool was used up the company expired. Even dealers who had based their whole business on the system finally had to give up because non-scheduled deliveries drove them out of business.

As you might imagine, anyone who finally succeeded in building and operating a digital group machine became one of an exclusive brotherhood who were one of the loyal group of users. Long after the demise of the company, the user groups carried on, and there were even third-party small manufacturers who made compatible equipment such as communication boards, floppy disk systems, and speech boards. One of these was Aeon Electronics, also of Denver Company, who made equipment well into 1983. Finally, even the user groups gave up, and the entire concept died.

Back to PC History