Microcomputer - History

History

Although they contained no microprocessors but were built around transistor-transistor logic (TTL), Hewlett-Packard calculators as far back as 1968 had various levels of programmability such that could be called 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. It is suspected that HP was reluctant to call them "computers" because it would complicate government procurement and export procedures.

The Datapoint 2200, made by CTC in 1970, is perhaps the best candidate for the title of "first microcomputer". While it contains no microprocessor, it used the 4004 programming instruction set and its custom TTL was the basis 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 discrete transistor–transistor logic instead of a microprocessor, but functioned like a microcomputer in most ways. It was marketed as an educational and hobbyist tool, but was not a commercial success; production ceased shortly after introduction.

In 1972, for the first time is marketed a solid state computer designed with a microprocessor (the Intel 8008 8-bit microprocessor). This machine the Micral-N, was created by a Frenchman François Gernelle of the company R2E. In 1973 this machine is widely named in the entire world a microcomputer. Since this machine, all computers designed with a microprocessor, personal computers, workstations even servers, will be called microcomputers.

In 1972, a Sacramento State University team led by Bill Pentz built the Sac State 8008 computer, able to handle thousands of patients' medical records. The Sac State 8008 was designed with the Intel 8008. It had a full set of hardware and software components: a disk operating system included in a series of programmable read-only memory chips (PROMs); 8 Kilobytes of RAM; IBM's Basic Assembly Language (BAL); a hard drive; a color display; a printer output; a 150 bit/s serial interface for connecting to a mainframe; and even the world's first microcomputer front panel.

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. These machines were 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.

By 1977, the introduction of the second generation, known as home computers, made microcomputers 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 (PC compatible).