The History of the Personal Computer - Part One: Before The IBM PC

Pretty much every home has a PC these days. Technically you have one in your hand in the form of a smartphone, depending on what your definition of 'personal computer' is. The lines used to be a lot clearer: presently you have a choice of a Mac or a PC. Macs are also PCs but no one calls them that. Macs weren't even called 'Macs' originally, they were 'Apples'. And why can't you still buy a PC from IBM these days, when they invented the PC to begin with? Or can you and did they? When you start to ask questions like this, it becomes clear that very few people know the full history of how PCs came to be a household item, after quotes like "I think there is a world market for maybe five computers" from Thomas Watson, president of IBM in 1943. To be fair, computers were as big as houses back then but, even in 1977, after the personal computer had come into being, the founder of one of the biggest computer manufacturers in history said "There is no reason anyone would want a computer in their home." How wrong he was...

Charles Babbage's Difference Engine
The history of computing arguably begins with the abacus, as computers were originally intended for one thing only: not to make our lives easier, but to solve problems. We humans have always been aware of our limitations: that there are certain tasks that we are largely incapable of completing accurately, reliably and in a timely manner (aside from the occasional exception). When Charles Babbage invented his Difference Engine in the 1820s, it was to solve a specific problem. Mathematics was used widely in science, engineering and navigation and the slide rule was the 'calculator' of the time. The device has limitations, however, so tables of numbers such a logarithms and trigonometric functions were pre-calculated (by people called 'computers') and printed so that answers could be looked up quickly when they were needed. Problems emerged with these 'log tables' because of errors - multiple publishers offered different solutions to the same equation and this is a significant issue when you're trying to navigate a ship. The Difference Engine was specifically designed to solve this problem, by calculating these logs accurately and even printing them onto conveniently-sized sheets. Unfortunately Babbage's invention was well ahead of its time and wasn't recognised for its potential so he was unable to secure the funding required.

Intel's 4004 [source:]
I'm going to skip most of the 20th century, because this is the history of personal computing. Although significant developments did indeed take place in the field of computing, particularly in the miniaturisation of components, prior to the 1960s, The PC largely came about thanks to the invention of the microprocessor. The first computers were mechanical devices. Following the introduction of electricity, experimentation led to many interesting discoveries, but very few applications. As early as the late 1800s, ways to manipulate the flow of electrons were being discovered, leading to the invention of the vacuum tube in 1907 and thus the next generation of computers. The reason I'm mentioning this is that it's the precursor to perhaps the most significant discovery of all - the semiconductor. A semiconductor is a material that can both conduct and insulate, depending on certain conditions. Being able to manipulate electrons on a microscopic scale led to the invention of the integrated circuit and thus the microprocessor. It is the birth of this device that shifted computer usage from terminals and mainframes into the hands of individuals.

Frederico Faggin [source: bbci]
Pretty much one man, Frederico Faggin, and one company, Intel, are responsible for the first commercially-available, one-chip CPU, the 4004. Although they were supposed to just be making a bespoke chip for a Japanese calculator company, they ended up with something more general-purpose that could be programmed. They proved this by using one of their own chips to aid the process of making further CPUs in the Intellec 4 computer. The chip was also used in the first microprocessor-controlled pinball machine. Although small computers did exist prior to the invention of the microprocessor, such as the Kenbak-1, they were slow, cumbersome, used many chips and weren't particularly versatile.

The premise of a personal computer is one that can be used by an individual, is easy to use, and is cheap enough for a person to buy. Before this time, computers were generally huge, expensive, and owned by companies or institutions. If someone wanted to use a computer privately, they had to buy time credits to use one. Bill Gates famously began his computing career by hacking such a computer so he could use it for free. This is another premise of the PC: if it doesn't do what you want it to do, find a way to make it so!

The MCM/70 [source: wikimedia]
One of the first computers that was described as 'personal' was the MCM/70, which was demonstrated to the press in September 1973 (although not commercially available until a year later). It was based on Intel's successor to the 4004, the 8008, and was designed to solve the inefficiency of multiple users sharing processing time on a mainframe. As far as I can tell the MCM/70 only had one use - to write programs in APL, a scientific language used for complex calculations and mathematical analysis. As such, most users were still big companies and the military i.e. the same types of users that were on mainframes previously. The only thing that really qualifies the MCM/70 as 'personal' is in the literal sense, as it didn't make computing available to the masses.

The MITS Altair 8800
That honour goes to the Altair 8800, a computer you could build from a kit. It was based on Intel's latest CPU, the 8080, as the MITS engineers felt the 8008 was not powerful enough. Although low sales were expectated, the Altair was snapped up by hundreds of thousands of hobbyists. One key aspect of the Altair was its bus (the way data travels between the CPU, the RAM and other components). Completely by accident, the computer had to be designed in such a way that all these components were on removable boards. This led to the use of something called a 'backplane'; a dedicated circuit board with connector sockets on it so that cards could be plugged in, expanding the functionality of the computer. The S-100 bus was born and became the de-facto standard on subsequent PCs for a number of years. It allowed many computers to use the same hardware add-ons, and was technically the first standard many manufacturers claimed 'compatibility' with.

Using the Altair was an experience that most people will never have to endure. Commands were fed into the computer by configuring the switches on the front panel so they corresponded with whichever opcode (from a list of instructions the CPU can carry out) the user wanted. Some data would then usually be entered and so on. You would eventually receive visual output in the form of an array of LEDs on the front panel and you would have to attach a terminal if you wanted to view output on a screen. Altair BASIC, the computer's programming language, was written by a couple of guys called Bill Gates and Paul Allen from a company called Micro-Soft.

Anyway, the Altair sold many more than was expected, and basically kicked off the microcomputer revolution from which all others followed. Being able to write and read machine language in binary, however, restricted these 'first generation' PCs from achieving wide popularity, limiting their audience largely to hobbyists and scientists. In the following months, rapid advances in technology, along with low component prices, made it possible for the next generation to introduce a keyboard and a monitor for input and output of human language. BASIC found itself as the standard for programming, and computers could now plug into a regular TV.

An original Apple I [source:]
The first meeting of the Homebrew Computer Club took place in March 1975 in Silicon Valley and was initially formed to help Altair owners build their kit. It also attracted a number of enthusiasts with a background in electronic engineering and programming. One of those enthusiasts was Steve Wozniak. He, like Gates, also got into trouble at school for hacking the institution's computer system but eventually graduated from University and got a job at Hewlett Packard designing calculators. After seeing the Altair, Woz designed the first Apple computer in 1976, financing and constructing the first 50 boards with the help of his friend, Steve Jobs. Only 200 were made in total before the Apple II was introduced a year later.

1977 was the year the personal computer really came into being and, depending on who you ask, one of the following three computers has a claim as the first genuine PC:

The Apple ][

The first Apple was not a 'proper' computer. It didn't have a case, a keyboard or a power supply. The second Apple did. Most importantly, where hobbyists had been the previous market of small computer makers, the Apple II was aimed at businesses and home users. It could be connected to a standard TV, included a pair of paddles for gaming and could display colour, which was unheard of among consumer-grade computers. The inclusion of Apple's version of BASIC in the computer allowed users to write their own programs without having to buy any additional software, and a cassette deck could be used to store data. The Apple ][ was also the first computer that had a 'killer app' i.e. a piece of software that was so useful you bought the computer just to have it. That software was Visicalc, the first digital spreadsheet. It caused an explosion of sales: between September 1977 and September 1980, this one computer took Apple's sales figures from $775,000 to $118 million, and the rest is history.

The Commodore PET

Folklore has it that Steve Jobs attempted to sell the Apple ][ concept to Commodore, a major manufacturer of calculators at the time. They considered Jobs' offer to be too expensive and Commodore's notorious owner Jack Tramiel demanded that his engineers come up with their own computer in 6 months. The PET 2001 was the first all-in-one home computer, with a built-in monitor and tape drive. Where the Apple ][ sold well to home users, the PET took a stranglehold on the North American education market, thanks to its rugged build quality.

The Tandy TRS-80

The final member of the 'Trinity of 1977' was the TRS-80. You've probably heard of Radio Shack, perhaps by watching the film Short Circuit or something like that, who had a chain of over 3,000 electronics stores in North America owned by Tandy. Again, the Altair provided the inspiration behind this computer, which started development in 1976 and was originally meant to be a kit. Based on the fact that 'too many people can't solder', Tandy's engineers decided instead to create a pre-assembled computer. Their timing was perfect. It seemed everyone wanted a computer in 1977, and Radio Shack stores took a quarter of a million of advanced orders. Thanks to having its own factories, distribution networks and retail stores, Tandy were able to get their new computer out of the doors by Christmas and apparently outselling the Apple ][ by a factor of 3.

The next part will, hopefully, be coming soon.