SOL-20 (top shelf, right), an MITS
Altair 8800 (second shelf, left), a
TV Typewriter (third shelf, center), and an
Apple I in the case at far right
TTL precursors Although they did not contain any microprocessors, but were built around
transistor–transistor logic (TTL),
Hewlett-Packard calculators as far back as 1968 had various levels of programmability comparable to microcomputers. The HP 9100B (1968) had rudimentary conditional (if) statements, statement line numbers, jump statements (
go to), registers that could be used as variables, and primitive subroutines. The programming language resembled
assembly language in many ways. Later models incrementally added more features, including the
BASIC programming language (HP 9830A in 1971). Some models had tape storage and small printers. However, displays were limited to one line at a time. The
HP 9100A was referred to as a
personal computer in an advertisement in a 1968
Science magazine, but that advertisement was quickly dropped. HP was reluctant to sell them as "computers" because the perception at that time was that a computer had to be big in size to be powerful, and thus decided to market them as calculators. Additionally, at that time, people were more likely to buy calculators than computers, and, purchasing agents also preferred the term "calculator" because purchasing a "computer" required additional layers of purchasing authority approvals. The
Datapoint 2200, made by
CTC in 1970, was also comparable to microcomputers. While it contains no microprocessor, the
instruction set of its custom TTL processor was the basis of the instruction set for the
Intel 8008, and for practical purposes the system behaves approximately as if it contains an 8008. This is because Intel was the contractor in charge of developing the Datapoint's CPU, but ultimately CTC rejected the 8008 design because it needed 20 support chips. Another early system, the
Kenbak-1, was released in 1971. Like the Datapoint 2200, it used
small-scale integrated transistor–transistor logic instead of a microprocessor. It was marketed as an educational and hobbyist tool, but it was not a commercial success; production ceased shortly after introduction.
Early microcomputers In late 1972, a French team headed by
François Gernelle within a small company, Réalisations & Etudes Electroniques (R2E), developed and patented a computer based on a microprocessor – the Intel 8008 8-bit microprocessor. This
Micral-N was marketed in early 1973 as a "Micro-ordinateur" or
microcomputer, mainly for scientific and process-control applications. About a hundred
Micral-N were installed in the next two years, followed by a new version based on the Intel 8080. Meanwhile, another French team developed the Alvan, a small computer for office automation which found clients in banks and other sectors. The first version was based on LSI chips with an Intel 8008 as peripheral controller (keyboard, monitor and printer), before adopting the
Zilog Z80 as main processor. In early 1973,
Sord Computer Corporation (now
Toshiba Personal Computer System Corporation) completed the SMP80/08, which used the
Intel 8008 microprocessor. The SMP80/08, however, did not have a commercial release. After the first general-purpose microprocessor, the
Intel 8080, was announced in April 1974, Sord announced the SMP80/x, the first microcomputer to use the 8080, in May 1974. Virtually all early microcomputers were essentially boxes with lights and switches; one had to read and understand binary numbers and machine language to program and use them (the Datapoint 2200 was a striking exception, bearing a modern design based on a monitor, keyboard, and tape and disk drives). Of the early "box of switches"-type microcomputers, the MITS
Altair 8800 (1975) was arguably the most famous. Most of these simple, early microcomputers were sold as
electronic kits—bags full of loose components which the buyer had to solder together before the system could be used. The period from about 1971 to 1976 is sometimes called the
first generation of microcomputers. Many companies such as
DEC,
National Semiconductor,
Texas Instruments offered their microcomputers for use in terminal control, peripheral device interface control and industrial machine control. There were also machines for engineering development and hobbyist personal use. In 1975, the
Processor Technology SOL-20 was designed, which consisted of one board which included all the parts of the computer system. The
SOL-20 had built-in EPROM software which eliminated the need for rows of switches and lights. The
MITS Altair just mentioned played an instrumental role in sparking significant hobbyist interest, which itself eventually led to the founding and success of many well-known
personal computer hardware and software companies, such as
Microsoft and
Apple Computer. Although the Altair itself was only a mild commercial success, it helped spark a huge industry.
Home computers By 1977, the introduction of the second microcomputer generation as
consumer goods, known as
home computers, made them considerably easier to use than their predecessors because their predecessors' operation often demanded thorough familiarity with practical electronics. The ability to connect to a monitor (screen) or TV set allowed visual manipulation of text and numbers. The
BASIC language, which was easier to learn and use than raw machine language, became a standard feature. These features were already common in
minicomputers, with which many hobbyists and early produces were familiar. In 1979, the launch of the
VisiCalc spreadsheet (initially for the
Apple II) first turned the microcomputer from a hobby for computer enthusiasts into a business tool. After the 1981 release by IBM of its
IBM PC, the term
personal computer became generally used for microcomputers compatible with the IBM PC architecture (
IBM PC–compatible). == See also ==