Development of the Personal Computer in the 1970ís
Personal Computers (PCís) are everywhere. I am sitting at my desk right now writing this report on my PC. It seems like these days we take computers for granted. Almost everyone has one. Teachers assign projects that almost completely require the use of a computer. Where did this explosion of PCís come from, though? Just a few short years ago you were lucky to have a computer. About 25 years ago people would have called you crazy if you said you had a personal computer. Thatís because before 1975 there were no personal computers that were available, or affordable, to the general population. In fact, it wasnít until much later that there really was a personal computer that anyone could use. The 1970ís served as a launching pad for the personal computer industry to blast off into the future.
In the early 1970ís computer hobbyists were starting to show frustration at the current situation involving computers. At the time the only way anyone could use a computer was to access a mainframe through a terminal on a time-sharing basis. What the hobbyists wanted was to be able to access their files any time they wanted, even if they were on a business trip. They wanted to be able to play games without someone yelling at them to get back to work. They wanted their own personal computer (Campbell-Kelley and Aspray 237-238; Triumph). Some people were already experimenting with building computers. In 1971 Steve Wozniak and Bill Fernandez built a simple computer out of parts that were rejected by local companies. This computer, which they called the "cream soda computer," worked with lights and switches and is considered by many to be the first personal computer (Polsson). This wasnít really satisfying, though. What hobbyists wanted was a real computer that they could call their very own. This frustration was being voiced in the major electronics magazines at the time, the main two being Popular Electronics and Radio Electronics. Soon both these magazines were putting out a call for an article on building a personal computer (Triumph; Freiberger and Swaine 27-29; Shurkin 307). This wouldnít have been possible a few years before, and it was a series of incredible advances in electronics that made it possible.
In the early 1970ís calculators were very popular. They had recently become much easier to manufacture due to the advent of the integrated circuit and large-scale integration (technology that put the equivalent of 100 transistors on a single chip). This same technology made the Intel 4004, the first microprocessor ever built, and the 8008 processor chips possible (Freiberger and Swaine 29). With this development in the manufacture of calculators Ed Roberts, founder of Micro Instrumentation Telemetry Systems (MITS), decided to turn all of his companies efforts toward manufacturing calculators (Freiberger and Swaine 31-32). This decision was very poorly timed, though. In 1974 two major developments in the semiconductor industry materialized. One was the trend of semiconductor companies to begin developing their own consumer products, and the other was the refinement of the early microprocessors (Freiberger and Swaine 32-33; Shurkin 309). The first development killed Roberts, and the second one saved him.
Ed Roberts is considered by many to be the founder of the personal computer. In 1974 many semiconductor companies, such as Texas Instruments, started making their own calculators and selling them to the public. Since companies like TI didnít have to buy the parts for their calculators from other manufacturers they could sell their product for much less than MITS could. By early 1974 MITS was going broke (Freiberger and Swaine 32, Triumph). This was the same time that Les Solomon, editor of Popular Electronics was in desperate need of an article on a personal computer kit. At this point Roberts made a critical decision, he decided he would build a kit computer (Shurkin 307; Campbell-Kelley and Aspray; Triumph).
The first thing Roberts had to do was figure out how he was going to build a computer. His first decision was on what processor to use. Intel had recently released the 8080 microprocessor, which was similar to the 8008, but infinitely more powerful. This is the processor that Roberts decided to use in his machine (Freiberger and Swaine 31; Kidwell and Ceruzzi 92-93). There were other candidates, though. Motorola had recently released the 6800 processor. Roberts turned that down because one of his friends told him that he had tried to implement BASIC, a high level programming language, on the processor and it was nearly impossible (Freiberger and Swaine 31). The largest factor in Robertís decision, though, was the price factor. Intelís processors sold for $360 a piece, but Roberts was sure he could talk them down. He didóto $75 a piece. This was an amazing deal, but of course it required Roberts to buy in volume (Freiberger and Swaine 31; Shurkin 308; Triumph). This was no problem, though, because Roberts needed to sell a lot of something to stay in business.
Roberts immediately began work on his design. He worked out a rough sketch of what he wanted and then handed the designs over to his engineers. Roberts wanted was an open architecture, he wanted his computer to be easily expandable. What this required was a number of uniform expansion slots and a way to connect them all together. The solution to this was a bus structure. A bus is a channel for data or instructions on a computer. Normally it is a parallel channel with many different signals passing simultaneously. The bus on Robertís computer had 100 separate channels and it was later dubbed the s-100 bus (Freiberger and Swaine 32-33).
While the engineers were finishing up the physical designs of the computer it was still without a name. Many suggestions were made, but Roberts refused them all. What finally happened is one day, very close to itís release, Robertís was sitting around his house and his daughter, Lauren, was watching Star Trek. He ask her what the name of the computer on Star Trek was, but she replied that she thought it was just "computer." Next he asked her what she thought he should call his computer. Lauren replied very simply "Why donít you call it Altair? Thatís where the Enterprise is going tonight." (Freiberger and Swaine 34) And the name stuck. When it was released Robertís computer was named the Altair 8800, the 8800 part of the name coming out of Intelís 8080 processor.
The Altair 8800 debuted on the cover of Popular Electronics magazine in January 1975. The picture on the cover was actually only a mock up, the first Altair was lost in the mail, so they had photograph an empty box (Triumph; Campbell-Kelley and Aspray 240; Freiberger and Swaine 34-35). The Altair was an instant success. As soon as the article debuted, orders started flooding in to MITS. As Les Solomon said "Two thousand people sent checks to an unknown company" (Freiberger and Swaine 37). The Altair shipped as a kit, you had to put it together yourself. Putting it together took considerable knowledge of electronics. It also had the annoying tendency to not work. Despite these facts, though, it continued to sell very well. Hobbyists were elated with the fact that they could own their own personal computer (Triumph; Freiberger and Swaine 38; Kidwell and Ceruzzi 94).
The biggest turn-off of the Altair, though, was itís sheer uselessness. All input was done through a series of switches on the front panel of the Altair, and all output was given in the form of flashing LEDís on the front panel just above the switches (Triumph). The kit shipped with the mainboard (the board that connected all the other parts), a processor card (a card that plugged into the mainboard which contained the processor), and 256 byte memory card (a byte is 8 bits, or binary digits. Therefore a byte represents 28 or 256 possible values) (Kidwell and Ceruzzi 95). There was no form of permanent storage. This meant that any time you turned off the Altair everything you had done would be lost. Programs had to be entered through the switches on the front panel, in machine language (the primitive language of the processor), and in binary (ones and zeros). To enter each instruction one had to set eight switches, and then flip a ninth to load the instruction. This hassle didnít turn out to be an incredible problem, though, because the Altair only had 256 bytes of memory. Since each instruction was one byte long, it could only store 256 instructions, or pieces of data, at one time. This is a very small amount. So the question arose, what could you actually do with this thing? (Triumph)
The first people that actually came up with a use for the Altair were Bill Gates and Paul Allen. When they saw the ad on the front of Popular Electronics magazine for the Altair they knew instantly that they had found their calling (Shurkin 309). Almost immediately they called up Ed Roberts and told him that they had a version of BASIC for his computer. Roberts had been getting many offers, so he told them what he was telling all the other software developers, if they could show it to him he would sell it. So Gates and Allen worked for the next six weeks on a BASIC interpreter for the Altair, and when they finally showed it to Roberts it worked. Although all it did was simply announce it presence, it was functioning and Roberts agreed instantly to sell it (Campbell-Kelley and Aspray 241-242). By this time Gates and Allen had formed a company they called Micro-Soft (later to be changed to Microsoft). They decided that instead of selling the product to Roberts they would lease it to him. BASIC was what the Altair needed, and it led to a whole series of software and expansion cards for the Altair (Campbell-Kelley and Aspray 241-242; Shurkin 309).
One of the products that was a direct result of Microsoft BASIC was the memory expansion card. BASIC required 4096 bytes of memory to run, much more than the standard 256 that came with the Altair. This led to the 4k memory expansion card (k refers to kilobyte, which is 210 or 1024 bytes) (Freiberger and Swaine 45). The first memory expansion cards were made by MITS, but they had problems. The major problem was that they didnít work, literally. This led many manufacturers to make their own 4k memory cards, which did work. Soon MITS was loosing a tremendous amount of money on memory expansion cards and they decided to link the price of BASIC to the purchase of memory cards. BASIC sold for $150 to people who bought the cards, while it sold for $500, more than the cost of the Altair itself, to people who hadnít bought the cards. Soon people began making their own copies BASIC and distributing it to their friends. By the end of the year the majority of the copies of BASIC in use had been pirated (Freiberger and Swaine 45).
One of the first groups that developed out of the personal computer revolution was the Homebrew Computer Club. The meetings started in the back of the founders garage, but the club soon grew so large that they had to rent a lecture hall at Stanford. These meetings were the breeding ground for a new generation of geniuses, and a new generation of companies. Most of the members were hobbyists and enthusiasts with moderate to advanced electronic abilities. At the meetings all kinds of questions about computers and electronics in general were answered (Triumph; Freiberger and Swaine 104-106). It also served as a breeding pit for new uses of the Altair. One of the most famous of these "uses" was demonstrated by Steve Dompier. At one of the meetings Steve went up to the front of the auditorium with his Altair and a radio. He sat there for a few minutes laboriously keying in a program. When he was done he set the radio on top of the Altair and started to run his program. What happened Amazed everyone, the radio began to play music. By altering the speed of the looping of his program, Steve had made the radio play music (Triumph; Freiberger and Swaine 104-106). This symbolizes the creative spirit that was a part of the Homebrew Computer Club.
One of the most well known companies that formed out of this club was Apple Computer, founded by Steve Wozniak and Steve Jobs. Steve Wozniak was an electronic genius. He had built a modified version of the Altair on his own, and it featured a keyboard for input and a monitor for output, along with .several other enhancements. This computer usually attracted quite a crowd at the club, and that is how he met up with Steve Jobs (Triumph; Shurkin 310; Freiberger and Swaine 203-205). Jobs was not the technical genius that Wozniak was, but he had considerable experience. Jobs was more of a visionary, and he saw a vast potential in Wozniak (Campbell-Kelley 244-245). At one of the meetings Jobs suggested to Wozniak that they start a company and build computers. Wozniak was very enthusiastic, and Apple Computer was formed.
The first product that Jobs and the "Woz" put out was the Apple I. The Apple I was basically just a mainboard. The user had to design the adapters for any input or output devices themselves, along with the power supply. Despite itís primitive design, the Apple I had moderate sales (Triumph; Freiberger and Swaine 198). What made the company famous, though, was Jobs next big idea, what would become the Apple II.
Jobs had a vision. He had a vision of a computer that anyone could use. It would be everything you needed all in one, and it would be cheap enough for anyone to buy. This seemed like only a dream, but if anyone could design this computer, Steve Wozniak could. Wozniak was an incredibly gifted engineer and he did wonders in designing the Apple II (Freiberger and Swaine 202-203). It was a work of brilliance. It had everything a computer needed, and it came in a sleek-looking case. A keyboard, mainboard, processor, RAM, everything except the monitor was included with the Apple II. The Apple II also had a built-in BASIC interpreter and, most importantly, it supported color graphics. This meant games, games, and more games. And despite all these features the Apple II was fairly affordable. It had a base price of $1200, which was more than most other products at the time, but the excess price was well worth the added functionality. Plus the Apple II had an open architecture, which meant it could be added to and expanded upon (Freiberger and Swaine 202-204).
Another thing that set the Apple II apart from all the other personal computers was itís disk drive. Right away Wozniak and Jobs realized the problem of storage space on the Apple II. Cassette tapes were too slow and unreliable, as were most conventional storage devices at the time. Immediately Jobs and Wozniak turned to the floppy drive. It was fast, accurate, and convenient. Wozniak hadnít worked much with disk drives before, but he had some knowledge and he learned fast. He spent week after week refining his design, replacing multiple chips with one that could do the same thing (Triumph). The timing involved with such a precise device also proved difficult, but once again Wozniak overcame the obstacles. This lead to the smallest, fastest, cheapest, and most reliable disk drive controller that had ever been built (Freiberger and Swaine 225).
The Apple II experienced great sales right from the start, but it needed something else to completely dominate the market. That something else was a "killer application" (Triumph). It needed some piece of software that would, in itself, justify buying an Apple II. That killer application turned out to be VisiCalc, short for Visible Calculator. VisiCalc was developed by a business student named Dan Bricklin. At the time he was studying, all tables of data had to be done by hand. When one piece of data was changed, someone had to go back and recalculate the whole chart. Dan Bricklin had a vision of an application that would take huge tables of numbers have the computer handle all the computation process. What was created was the first spreadsheet program, although that term was not present then. VisiCalc allowed people to take large financial tables, where all the data values depended on all the other data values, and process them automatically. If you found out that you needed to change a number at the beginning of the table, VisiCalc would update all the other numbers for you (Campbell-Kelley and Aspray 250-251; Triumph; Shurkin 311).
VisiCalc was an immediate success. Sales of the Apple II soared. By 1980 Apple estimated that over 1/5 of itís sales were driven by VisiCalc (Campbell-Kelley and Aspray 250-251). As sales of Apple IIís rose, so did the sales of enhancements for the Apple II. Wozniak tried to build accessories that would make the Apple II attractive to people outside the business world. He developed many connectors for various printers and modems. He also made a serial card and a ROM (Read-Only Memory) card. Soon more and more manufacturers signed on to make Apple IIís and production began to soar (Freiberger and Swaine 216-217). The Apple II became the first personal computer that was meant for anyone, and it revolutionized the personal computing industry.
There were also many other computers that came out during the 1970ís, but none of them were as revolutionary as the Altair 8800 or the Apple II. Most of them were either clones of the Altair or pathetic attempts at an Apple II. None of them shaped the industry in the way that the Altair and the Apple II did. The Altair was the first PC, it provided a new dimension to computing and a basis for everything to follow. The Apple II was the first step, and in fact it was a huge leap, toward a modern personal computer. Both of these products provided a launching pad for the personal computing industry to blast off into the future of computers, and it was almost a flawless launch.
Campbell-Kelley, Martin., and William Aspray. Computer: A history of the Information Machine. New York: BasicBooks, 1996.
Freiberger, Paul., and Michael Swaine. Fire in the Valley. Berkeley, California: Osborney McGraw-Hill, 1984.
Kidwell, Peggy A., and Paul E. Ceruzzi. Lanmarks in Digital Computing. Washington: Smithsonian Institution Press, 1994.
Polsson, Ken. "Timeline of Microcomputers." 1998. <http://www3.islandnet.com/~kpolsson/comphist.htm> (19 Apr. 1998).
Shurkin, Joel. Engines of the Mind. New York: W.W. Norton and Company, 1996.
Triumph of the Nerds. Videocassete. Written and Narrated by Bob Cringely. Director Paul Sen. Producers John Gau and Stephen Segaller, 1996.