Nat Wadsworth

It was in September 1972, when Nathaniel “Nat” G. Wadsworth (30 May 1943-25 Nov 1998), a 29-year-old electrical engineer, decided to leave his job to create a new kind of computer. Working with a few friends (Bob Findley (who became his main engineering and business partner), Fred Lucas, and Frank Zawacki) in his cottage in Milford, Connecticut, soon he started designing his computer around the new Intel 8008 microprocessor.

Nat Wadsworth show interest in electronics as a teenager, when he was a Ham radio operator since the age of 12, and at 14 made early business assembling electronic kits (heathkits). He dropped from high school and ran away from home at age 17 to join the US Navy, where he served as a shipboard radio operator in the western Pacific. Discharged from the service in 1961, he attended night school, then found a job and entered the University of Connecticut to study electrical engineering. His interest in computers began in 1965 when he worked at the electro-mechanical department of Bunker Ramo, an American electronics company. He worked on DEC PDP-5, and PDP-8 at the end of the 1960s. He even managed to buy his own PDP-8 (at the time only large companies and universities could afford that, but Nat was happy to find a cheap used machine) and wrote a lot of programs in his spare time.

In 1970 Nat got his degree (BSEE) Cum Laude from the University of Connecticut. In the autumn of 1972, he attended a seminar given by Intel Corporation, designed to introduce engineers to Intel’s new 8008 CPU-on-a-chip. He quickly became convinced that he could use the 8008 to replace a great deal of the logic chips he was using in the design of a product underway at the firm where he was then employed as an electronic engineer. His enthusiasm for the 8008 however was not appreciated by management, so he decided to leave and begin his own business.

In 1973 Wadsworth and Findley found the company Scelbi Computer Consulting (an anacronym for SCientific ELectronic BIological). Its Scelbi-8H microcomputer (H standing for hobby, as Nat’s plan was to market his computer at a low price to hobbyists through advertisements in amateur radio magazines) is now recognized as being the first microprocessor-based computer kit to hit the market (the earlier Micral wasn’t a kit, as it was only available in fully assembled form, while Scelbi was available both in kit form and as fully assembled).

The first market announcement for Scelbi-8H was a tiny advertisement in the back of the March 1974 issue of QST, an amateur radio magazine. According to the advertisement, Kit prices for the new Scelbi-8H mini-computer start as low as $440! Actually, with 1K of RAM, the price was some $500. Unfortunately, sometime in the middle of 1974, Zawacki’s and Nat’s close friendship ended, and Zawacki left the company, taking SCELBI’s major investors with him. This affected the company, in that future projects had to be financed by revenues, alone.

Scelbi-8H (see a product brochure) was based on Intel’s first 8-bit microprocessor—8008 (launched in April 1972), the predecessor to the Intel 8080 CPU, used in the Altair 8800. The 8008 was capable of addressing 16Kb of memory and started the design of the first series of microcomputers. The Scelbi-8H had 1K of RAM as a minimum, and an additional 15K of RAM could be purchased for $2760. It had a cassette tape interface, as well as Teletype and oscilloscope interfaces.

After the first advertisement in QST magazine, Scelbi-8H (see the nearby image) appeared in Radio-Electronics and later (September 1975) in BYTE magazine.

Scelbi-8H soon had competitors. In July 1974 Radio-Electronics published plans for a similar 8008 machine, called the Mark-8, that skilled hobbyists could fabricate for the cost of parts. Companies like MITS started selling systems based on more capable processors, such as the 8080 used in the MITS Altair 8800. SCELBI responded by introducing the Scelbi-8B model with 16K of memory (the upper limit of the 8008) and more software available for it (see an ad in Byte magazine).

No high-level programming language was available for the Scelbi-8H in the beginning (see the Users Manual of Scelbi-8H). In 1975 Wadsworth wrote a book, Machine Language Programming for the 8008 and Similar Microcomputers, that taught the assembly language and machine language programming techniques needed to use the 8H. The book included a listing of a floating point package, making it one of the first examples of non-trivial personal-computer software distribution in the spirit of what would much later become known as open source. Because of the similarities between the 8008 and the 8080, this book was purchased by many owners of non-SCELBI hardware. In 1976 Wadsworth and Findley authored a book for computer games.

As the Scelbi-8H did not sell well, it was discontinued by December 1974, and the next year an improved business-market version (named Scelbi-8B), was introduced. Some 200 Scelbi-8B boxes were produced in 1975 and sold at about $580 each, but it also did not become a big market success (as the production cost of the kit was about $1000, so money lost on hardware was recovered through software sales).

Scelbi Computer Consulting discovered that they made more money selling software books than hardware, so by the late 1970’s the company had discontinued making hardware and switched to highly documented software published in book form, including many games, a monitor, an editor, an assembler, and a high-level language dubbed SCELBAL (a dialect of BASIC, that incorporated Wadsworth’s floating-point package), to compete against Altair BASIC.

In 1982, Wadsworth sold the SCELBI publishing business to Hayden Publishing and started exploring pocket computer technology. In 1988, he had the design done for a new pocket computer that he thought would revolutionize the industry. He had parts on hand and was ready to build the first production units when his heart stopped again (he had already survived several heart attacks and two heart surgeries). He survived again, but with heavy damage to his body and mind. On 25 Nov 1998, Nat’s heart stopped again, this time forever.