Computer users soon learn that the miraculous powers of personal computers are based on the avoidance of error.
It is a difficult task to define the term personal computer, but one of the popular definitions is containing the following criteria:
• small, stand-alone
• general purpose
• advanced microelectronics technology (microprocessor)
• operated by a single individual, interactively
• no requisite computer training
• affordable by an individual or small group
It appears the first computer, fulfilling the all abovementioned conditions is Micral N. It was introduced in early 1973, powered by Intel’s 8008 chip, and was the first commercial non-kit computer based on a microprocessor. It was conceived in France by François Gernelle (born 20 December 1944), an ex-engineer at Intertechnique (a french high-tech company, specializing in electronic measurement for aviation). The term microcomputer first appeared in print in reference namely to the Micral.
The Micral-N was initially developed for the I.N.R.A. (French National Institute for Agronomic Research) which was looking for a computer for process control in its hygrometric measurements but didn’t have sufficient budget to buy the lowest “mini” at the time (e.g. Digital Equipment PDP-8), so Gernelle proposed to make a computer for them for half the price. The development began in July 1972, in a hut in Chatenay-Malabry (Paris suburbs), with Gernelle and three of his collaborators: Benchetrit (software engineer), Alain Lacombe (electrical technician), and Jean-Claude Beckmann (in charge of the mechanical part).
In 1973-74 François Gernelle applied for patents for different features of Micral in France (patent FR2216883), Germany (patent DE2404886), Netherlands (patent NL7401328), Japan (patent JP50117333), and the USA (patent US3974480 for Data Processing System).
The first Micral (see the nearby image) was delivered to the INRA in January 1973, and commercialized in February 1973 by the French company Réalisation d’Études Électroniques (founded in 1972 by Gernelle and his ex-colleague Andre Truong), for the amazing price (at the time) of FF 8500 (about $1750).
The 8008 CPU, that powered the Micral was essentially an improvement of Intel’s first microprocessor—4004 and was Intel’s first 8-bit processor. It was available as a DIL chip with 18 pins and was originally intended to be a custom chip for Computer Terminals Corp. of Texas (later known as Datapoint). CTC rejected the 8008 because it was too slow and required too many supporting chips, and when Intel offered it to the open market, it was not quite successful. The Micral’s CPU was working at 500 KHz (period 2µs), running approximately 50000 instructions per second. It was set on a bus and did have MOS memory, parallel and serial I/O cards, and a real-time system. In one word, it had all the characteristics of nowadays computers.
The software was written on an Intertechnique Multi-8 minicomputer, using a cross-assembler. Micral had a back-panel bus, the so-called Pluribus with a 74-pin connector. 14 boards could be plugged into a Pluribus. With two Pluribus, the Micral could support up to 24 boards. R2E developed many boards for Pluribus: a processor board, memory boards, channel boards named “channel-stack”, communications adapters, digital I/O boards, analog I/O boards, floppy disk, hard disk, and magnetic cartridges controllers. The computer used MOS memory instead of core memory. It had eight levels of interrupt and a stack. Micral was programmed with perforated cards and used a teletype as output.
An 8-inch floppy disk reader was added to the Micral in December 1973, following a command of the Commissariat à l’Energie Atomique. This was made possible by the pile-canal, a buffer than could accept one megabyte per second. In 1974, a keyboard and display were fitted to the Micral computers. A hard disk became available in 1975. In 1979, the Micral 8031 D was equipped with a 5″ 1/4 inches hard disk of 5 Megabytes made by Seagate.
The Micral processor board embarked on the 8088 with its addressing capability of 16 KB (address field 14 bits).
The following Micral computers successively used the Intel 8080 at 1 MHz (Micral G and Micral S), Zilog Z80 (Micral CZ), and Intel 8088 as microprocessors. The Micral M was a multiprocessor. The original SYSMIC operating system was renamed Prologue in 1978. The last Micral designed by François Gernelle was the 9020. In 1981, R2E was bought by Groupe Bull. Starting with the Bull Micral 30, which could use both Prologue and MS-DOS, Groupe Bull transformed the Micral computers into a line of PC compatibles. François Gernelle left Bull in 1983.
The Micral series was a rather successful market product. The company R2E sold about 90000 units of the Micral that were mostly used in vertical applications such as highway toll booths and process control.
The initial software available on Micral was application specific and the Prologue operating system was developed during the late 1970s. It was to be one of the operating systems available to PC compatibles.