The SCELBI-8H Computer: Everything You Need To Know

The SCELBI-8H was a personal computer that came in a kit form or assembled. It featured the 8-bit Intel 8008 CPU and 1,024 bytes of memory. The computer had its launch date in 1974, during the same timeframe as the Micral computer. The name SCELBI was an acronym for (Sc)ientific (El)ectronic (Bi)ological and was pronounced “sell-bee.”

Bob Findley and Nate Wadsworth were founders of the SCELBI Computer Consulting Inc., of Milford, Connecticut. This was a personal computer software and hardware company founded in 1973. The first product the company manufactured was the SCELBI-8H microcomputer. The machine was powered by the Intel 8008, which is a byte-oriented microprocessor. The 8008 that was from Intel was launched in April 1972.

They designed the 8008-based SCELBI-8H microcomputer, which is now recognized as the first microprocessor-based computer kit on the market. It’s important to note that the Micral wasn’t a kit since it was only available in fully assembled form. The SCELBI, however, was available in both kit form and fully assembled. It had five circuit boards and the company offered several devices with it including a keyboard, a teleprinter interface, and a cassette tape interface that could be used for data storage.

During the time of the launch date, the first market announcement for the Schelbi-8H was a tiny advertisement on the back of the March 1974 issue of QST, an amateur radio magazine. The SCELBI-8H had 1K of RAM as a minimum. Some kits could be purchased for less than $500. Prices varied, however, depending on if the computer was in kit form or assembled, and what devices came with it.  For example, an additional 15K of RAM could be purchased for $2,760. 

Five Facts about the SCELBI-8H Computer

• SCELBI-8H was based on the 8008 – the first 8-bit microprocessor.
• This was the predecessor to the Intel 8080 CPU that was used in the Altair 8800.
• The SCELBI-8H had a minimum 1K of RAM. 
• The 8008 was capable of addressing 16Kb of memory and was the first in a series of microcomputers.
• After the first advertisement in the QST magazine, SCELBI-8H appeared in Radio-Electronics and later in BYTE magazine.

SCELBI-8H: Specs

The following were a few basic aspects of the SCELBI-8H Computer when it was on the market:

• Price in Kit Form: $440 to $580
• Launch Date: Early 1974
• 1Kb RAM: This was expandable.
• Additional 15Kb available for $2,760.
• CPU: 8008
• Dimensions: 9 3/4 x 22 x 22 in.
• Quantity Built: 200
• Last Year Produced: 1975

The History of the SCELBI-8H Computer: What to Know

Back in the early 1970s, there was an increasing desire for a personal computer that could be used at home or in the office. The SCELBI-8H was one of the first of several that came out in the same time period.

Computer Consulting in Connecticut marketed the SCELBI-8H computer in March 1974. This particular personal computer was based on the 8008, an 8-bit microprocessor. Intel had come up with the 8H that contained 1K random access memory. The SCELBI-8H could be purchased either as a kit or fully assembled.

The microcomputer industry grew exponentially after Intel introduced the 8080 CPU in 1974. The 8080 was powerful enough to provide 64Kb of RAM and, therefore, build a practical computer. By 1975 the personal computer era had begun.

There wasn’t any high-level programming language available for the SCELBI-8H in the beginning (see the User’s Manual of SCELBI-8H). Then Nate Wadsworth wrote the book, Machine Language Programming for the 8008 and Similar Microcomputers. This book taught the machine language and assembly language techniques that were necessary to use the 8H. 

The book included a listing of a floating-point package. This made it one of the first examples of non-trivial personal-computer software distribution related to what would much later become known as open source. Because there were similarities between the 8080 and the 8008, owners of non-SCELBI hardware often purchased this book. 

It wasn’t long before SCELBI-8H had a competition. In July 1974 Radio-Electronics published plans for a similar 8008 machine. This was named the Mark-8. Companies such as MITS started selling systems based on more capable processors, such as the 8080 that was used in the MITS Altair 8800. SCELBIresponded by introducing the SCELBI-8B model with 16K of memory, which was the upper limit for the 8008. They also made more software available for it.

In 1975 two more competitors hit the market. These included the Altair and the IBM 5100. Bill Gates, who was a Harvard freshman at the time, and Paul Allen, put together a version of BASIC that would be used for the Altair. 

The computer was called Project Mercury and was considered the first portable computer made by IBM. Its $10,000 price, however, put it out of range of most of the hobbyists who might have been interested. The 5100 went primarily to educational institutions and business owners.

SCELBI Versions: Each Edition

• SCELBI -8H
• SCELBI -8B

Version 1

The first version was the SCELBI-8H. The H stood for the word “hobbyist.” This version had several distinct features. These included the following:

Eight slot backplane with several different cards: CPU slot, front panel card, data buffer and input slot, and an output port slot. There were also four memory slots that had a total of 4K. On the back chassis, a panel contained the following: parallel output and input ports, and the power supply connection.

Version 2

The second version was the SCELBI-8B. The B stood for business. This particular version had all the features of the SCELBI-8H but included support for 16K of memory. This was accomplished by adding an extra memory card and updating 4K memory modules.

The front panel card, CPU card, data buffer, input card, and output port card were all the same as the 8H version. The chassis was basically the same as the SCELBI-8H. However, there was an extra slot in the backplane for the extra memory card. This took more space at the top.

SCELBI-8H: The Public Response

When the SCELBI came on the market, the internet was not a regular part of our lives. This meant it was difficult for those interested in the SCELBI computers, which were primarily computer hobbyists at the time, to share information. Except for the newsletter put out by the Amateur Computer Society, there wasn’t much publicity.

The SCELBI-8H didn’t make an initial splash in the world with a big marketing campaign. The first market announcement was a small advertisement on 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 started as low as $440. With 1K of RAM, the price was $500.

Since the SCELBI-8H didn’t sell well, it was discontinued by December 1974. The following year an improved business-market version was introduced. This was called the SCELBI-8B. Approximately 200 SCELBI-8B boxes were produced in 1975. Each sold for about $580. This product, however, wasn’t a big seller either. The production cost of the kit was around $1,000. Less than 150 sets or assembled models were ever sold. By the end of 1975, systems with the improved 8080 processor greatly reduced the demand for any 8008 type of products. SCELBIComputer Consulting discovered that they made more money selling books than hardware.

By the late 1970s, 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 called SCELBAL. SCELBAL was a dialect of BASIC which incorporated Wadsworth’s floating-point package. This product competed against Altair BASIC. The publishing part of the business was sold in 1982.