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Personal Computers

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Personal Computers


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Personal computers have been so important to mankind for the last 30 years, changing our lives and almost taking over every field and aspect of society, so unlike other technologies they require a special section all for themselves.

Just like Generation Z (1993-2010) is considered the "Internet Generation" or "Net Generation" because they were born and grew up with Internet, Millennials were born and grew up with personal computers.

Early computers were introduced in the 40s and developed during the next three decades taking advantage of different technological breakthroughs. Back in those days computers were large, expensive and owned by large corporations, universities, government agencies, and similar-sized institutions.

At the beginning they were produced to do hard and multiple advanced scientific calculation and communication tasks during the post WW II cold war; as well as the space race.

During the 40s and first half of the 50s they were huge machines based on vacuum tubes which produced much heat and consumed lot of energy. The most famous computer of this era (1st generation computers) is the ENIAC. It was made up of 17,468 tubes, weighed 27 tons and took up 680 square feet (63 m2); this monster consumed 150 kW of power. Data and orders input and results output was possible through punched cards. However tubes burned out almost every day, leaving it nonfunctional about half the time. Users generally did not directly interact with the machine, they used to prepare tasks for the computer on off-line equipment, such as card punches. Once the job was finished, users collected the results. In some cases it could take hours or days between submitting a job to the computing center and receiving the output.

During the late 50s and throughout the 60s transitors replaced vacuum tubes (2nd generation computers). Transistors could perform more tasks per second, they were more efficient, consumed less energy, gave off less heat and took over less space, the latter leading to development of smaller computers. But they were still large, expensive and hard to use for normal consumers. The only way to communicate with them was through the difficult machine code which used binary numbers; there were not operation systems yet. The input and output was performed by a time-sharing system, multiple computer terminals let many people share the use of one mainframe computer processor. This was common in business applications and in science and engineering.

The model where one user had exclusive use of a processor came in the 60s with the advent of a different type of computer the minicomputer, the predecessor of the personal computer. The first ones to experiment with these computers were scientists or engineering university students with access to some of the first computers; they had access to applications like T-square an ancestor of current CAD programs and even to games like the 1961 Spacewar! created in the MIT. Nevertheless, despite being smaller they were still expensive with prices of tens of thousands of dollars, and large by today's standards, about the size of a refrigerator; so they were only available in scientific, educational or governmental institutions.

But the real change would come in the 70s. Minicomputers used early integrated circuit technology, which reduced their size, but the lack of a microprocessor made them still large for the regular market as well as costly. With the introduction of the microprocessor the integration of hundreds of transistors into a single microchip paved the way for smaller computers.

On November 15, 1971 Intel introduced the first microprocessor, the Intel 4004. It was followed in 1972 by the Intel 8008, the world's first 8-bit microprocessor. The 8008 was the precursor to other successful 8-bit microprocessors like the Intel 8080 and the Zilog Z80 released in 1974 and 1976 respectively.

With the introduction of microprocessors costs started to decline and the attention of electronics enthusiasts increased. So, hobbyist magazines started to publish build-it-yourself microcomputers kits articles. The kits were sold by mail order through advertisements in the magazines.

The first one was the Mark 8 computer, designed by Jonathan Titus and published in Radio Electronics Magazine in July 1974. But the magazine computer kit that would start the era of personal computers was the Altair 8800 published by Popular Electronics in December 1974 (actually it was the January 1975 issue but it was already available on newsstands a week before Christmas). The Altair was the one that changed everything, the main reasons, among others, of the this computer's success instead of the Mark 8 are the fact that it used the more powerful 8-bits Intel 8080, while the Mark's designers chose the Intel 8008 which lacked some internal parts that were thought necessary to a personal computer. Second, the Altair was offered as a complete kit and not a list of components to buy in order to build it; since back in those days it wasn't so easy for anyone outside the Silicon Valley to buy the components that made up the computer.

In 1970, electronic calculators were used only on laboratories, but by 1974 they were a common household item. Calculators and video games like Pong introduced computer power to the general public. There were Intel 8008 based computer systems available in 1974 but they were not powerful enough to run a high level language like BASIC. The Altair had enough power to be actually useful, and was designed as an expandable system that opened it up to all sorts of applications.

Since the Altair 8800 was a complete success it was also released in a assembled version.

At the beginning users should input the orders and data into the computer's memory as well as receive the output using a front panel of toggle switches, pushbuttons and LED displays. After a very short time I/O through a terminal was the preferred human/machine interface, and front panels became extinct. Soon a new company named Microsoft was founded to supply a BASIC interpreter for the systems. They had not operating system, so to start them up it was required to enter a machine language program by hand via front-panel switches.

It was the beginning, though difficult, after some years all these tasks would become easy to perform by anyone.

The Intel 8080 microprocessor, was followed by other microprocessors like the Zilog z80, Intel 8085, the successful 16-bits Motorola 68000 and the 8-bits MOS 6502 which was the least expensive full-featured microprocessor on the market but still comparable to the Motorola 68000 in functionality thus becoming one of the most popular 8-bits microprocessors.

Since then different companies started releasing the first commercial personal computers based on these new microprocessors.

In 1976 Steve Wozniak designed the hand-built Apple I. His friend Steve Jobs had the idea of selling the computer. Thus the first Apple computer was released. Unlike other hobbyist personal computers, which were sold as kits, the Apple I was a fully assembled circuit board. However, users still had to add a case, power supply transformers, power switch, ASCII keyboard, and a video display. An optional board providing a cassette interface for storage was later released. All in all 200 units were sold. It used a MOS 6502 processor at 1Mhz.

In 1977 the first successful commercial personal computers were released; the Apple II, PET 2001 and TRS-80.

First the Commodore PET (short for Personal Electronic Transactor) was released in June 1977 when it was introduced at the Consumer Electronics Show. Based on a MOS 6502 processor, it came with either a 4KB or 8KB memory and a built-in green monochrome video monitor with 40×25 character graphics controlled by a MOS 6545 display chip. The keyboard was like a calculator instead of a typewriter keyboard. Programs were saved in a built-in cassette recorder. The initial price was $795. However at the beginning it had many technical problems, a terrible reputation for lack of support of both users and dealers and lots of complains. Nevertheless in overseas markets like the United Kingdom it was a complete success, howver we cannot say the same for the United States, where it did well in the educational market thanks to the promotion of giving a free computer for every two that a school bought. This bargain made it harder for the much more expensive Apples and Radio Shack TRS-80s to get into that market, although the teachers much preferred them. So it success was based mainly on the overseas success.

The Apple II was factory built, in-expensive and easy to learn and use. The first ones went on sale on June 5, 1977 with a MOS Technology 6502 microprocessor running at 1 MHz, 4 kB of RAM, an audio cassette interface and the Integer BASIC programming language built into the ROMs. The Apple II was also the first personal computer capable of color graphics. It included internal slots for expansion, which were mounted in a streamlined plastic case. However, the monitor and I/O devices were sold separately. Apple DOS was added to support the diskette drive; the last version was "Apple DOS 3.3". At the beginning it didn't sell well, but after 1979 it caught up with other computers. Its lifetime was about eight years longer than other machines of the time, and so achieved the highest total sales. By 1985 2.1 million had been sold and more than 4 million Apple II by the end of its production in 1993.

The Radio Shack's TRS-80 selling for about $500 complete with video monitor and BASIC took the personal computer market immediately.  It used a fast Z-80 processor, a cassette recorder for program and data storage, the basic model originally came with 4 kB of RAM, and later 16 kB. Later models incorporated disk drives and more memory. the Model III, housed in one case became the most popular personal computer in schools and homes rivaling the Apple II. Radio Shack also built other types of personal computers including the first practical laptop, the Model 100. Its cost was $599 US Dollars with everything, about $600 less that the Apple II if the latter included the monitor and I/O devices.

But the 70s meant just the introduction of personal computers, the real installation of them in society happened in the 80s. Component prices continued to fall, and many new companies entered the computer business. This led to a wave of low-cost machines, that sold millions of units before the market collapsed in a price struggle in the early 1980s. Atari, Commodore, IBM and Texas Instrument would launch each their personal computer models, entering the hard competition but at the same time that commercial contest turned computers into an accessible tool for everyone, losing the "luxury" nature.

The Atari Models 400 and 800 were considered among the best personal computers for games and color graphics. They had a very large family of game software, but not much business software. They were based on the MOS6502 microprocessor, 8 KB but as memory prices continued to fall Atari eventually supplied the 800 fully expanded to 48 KB, using up all the slots. But the lack of good disk and peripheral support and the hard prices competion left Atari in a bad position. They were unable to compete effectively with Commodore, and only about 2 million machines were produced by the time the 800 was discontinued.

The Texas Instruments 99-4A used a TI 16-bit processor and was an excellent graphics computer.  It lacked easy expansion capabilities and required proprietary software. After entering in the prices struggle with Commodore, TI stopped production and sold out below $100 per computer. A total of 2.8 million units were shipped before the TI-99/4A was discontinued in March 1984.

In August 1981 IBM responded with the release of the IBM PC. Like the Apple II it was based on an open, card-based architecture, which allowed third parties to develop for it. It came with a Intel 8088 processor 4.77 MHz. Initially it came with an audio cassette for external storage, but it had an expensive floppy disk option. In 1983 the PC XT model was released. It added a 10MB hard drive in place of one of the two floppy disks, increased the number of expansion slots from 5 to 8 and discarded the use of cassette for storage. While the original PC design could accommodate only up to 64k on the main board, the architecture was able to accommodate up to 640KB of RAM, by means of expansion cards. Later designs increased the limit to 256K on the main board. It came with a rebranded version of MS-DOS, the PC-DOS.

One of the main features that made this model the most popular to our days is its modularity and expansion capabilities. The impact caused in society by the Apple II and the IBM PC, made Time Magazine in its January 3, 1983 issue, name the home computer the Machine of the Year instead of the Person of the Year; being the first time in the history of the magazine that an object was given this award.

In 1984, IBM released the IBM PC/AT built around the Intel 80286 microprocessor. This chip was much faster, and could address up to 16MB of RAM but only in a mode that largely broke compatibility with the earlier 8086 and 8088.

Another feature that made the PC the most successful computer model so far and still is the most used is its compatibility. When the 32-bit Intel 80386 microprocessor was released in 1986 other companies started making PC compatible systems, the Compaq Deskpro 386 being the first one; the era of IBM PC clones had begun, becoming the leading computer of the market since the 90s. Nowadays the term IBM PC compatible is not used for current systems because almost all the mainstream computers are based on the PC architecture. Today the only main competitor to PC is Mac.

But before the PCs took over the market in the 90s, other computer models would dominate the market during the 80s; the Commodore 64, the Spectrum (UK), Amiga, Macintosh and Atari ST.

The Commodore 64 was released in 1982 and it is the best-selling single personal computer of all times (The PC actually is a modular computer made up of an array of various compatible computers produced by different companies); during its lifetime, C64 sales totaled 30 million units. In the1983–1986 period, the C64 dominated the market with between 30% and 40% share and 2 million units sold per year, outselling all the other competitors. It is also considered as the computer that brought computers technology to middle-class households via creative mass-production, low prices and great functionality. It was also the favorite computer for gaming, about 10,000 commercial software titles were made for the Commodore 64 including games, development tools and office applications.

The Commodore 64 had a 1.023 MHz MOS 6510 microprocessor (a close derivative to the MOS 6502), a video chip VIC-II with a resolution of 320 × 200, 16 colors and a 40-column screen. It had a music synthesizer chip (SID chip). It had 64KB of RAM at a time when Apple had a maximum of 48KB. It also featured a 5 1/4'' floppy drive, the 1541 drive.

Then, in the summer of 1982 the home computer prices struggle started between Texas Instruments and Commodore, with Texas Instruments issuing a $100 rebate on the TI 99/4A, bringing the price down to $200. C-64's initial price was $595 but soon it was moved from the computer stores to mass merchants such as K-mart for $400, meanwhile Atari joined the competition with a $55 rebate on the Atari 400 and dropped the price on the Atari 800 to under $500. Commodore moved the C-64 from the computer stores to mass merchants such as K-mart for $400.

In 1983, Texas Instruments again cut the dealer's price of the TI 99/4A by $48 making the retail price $150. Commodore responded with a massive "trade-in" offer. They would give a $100 trade-in on any video game, or computer, against the purchase of a Commodore 64. Thus, people changed their old computers and turned them in on Commodore 64's for $100. So the retail price with a "trade-in" was $300.

Things were difficult for some companies; Texas Instruments was losing millions of dollars due to the high costs of production and low retail prices while Commodore's costs were so low that even at the depressed prices they actually made money on their computers. So Texas Instruments quit the home computer business after the big losses caused by the prices competition. By 1983 Commodore hit one billion dollars in sales and became the most popular computer of the 80s.

However, while in the American continent the Commodore 64 was the leading computer of the market and no computer could achieve same levels of sales; in the UK despite the popularity of the aforementioned computer, the Spectrum ZX was its main competitor. It was an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research Ltd. It had eight different models, ranging from the entry level model with 16 KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987. It came with a Z80 3.5 MHz microprocessor and 16 KB, 48 KB or 128 KB according to the model. It had a palette of 15 colors, seven colours at two levels of brightness each plus black, and an image resolution of 256×192. Sound output is through a beeper on the machine itself with the capacity of producing one channel with 10 octaves. The Spectrum is considered as the computer that introduced United Kingdom's IT industry.

Most early millennials remember having played with either the Commodore 64 or Spectrum thanks to the huge number of game titles released for both. A whole market related to them grew during the decade with over 10,000 game titles, game magazines and even entertainment books dedicated to both computers.

In 1983 Apple launched the first GUI-driven (Graphic User Interface) computer, the Lisa, then in 1984 it launched the Macintosh, the first successful mouse-driven computer with a GUI. It came with a Motorola 68000 microprocessor and it was initially introduced with 128 KB of RAM and later that year a 512 kb RAM model became available. It had no internal hard drive, and a single 3.5" floppy drive. Its initial retail price was US$ 2,495. The Mac was not an immediate success and would have to wait until the 90s to get popular and become by the 2000s one of the two leading computer models of the market, the PC and the Mac. During the 80s it was used by artists for its high quality graphics.

During the rest of the decade other computers would be released but no one achieved the levels of popularity of the Commodore 64.

The Commodore 128 released in 1985 was the last 8-bit machine commercially released by that company. It had a two-microprocessors design, including a 2 Mhz MOS 8502 and a 4 Mhz Z-80A. The Z80A was used to run a CP/M operation system instead of BASIC, as well as to initiate operating mode selection at boot time and run the computer as a Commodore 64. Like the C-64 it also featured a 5 1/4'' floppy disk drive, the 1571. However it did not achieve the commercial success of the C-64; and since the C128 would run virtually all C64 software, and because the next-generation, 32/16-bit home computers, primarily the Commodore Amiga and Atari ST, were gaining ground, relatively little software for the C128's native mode appeared (around 100–200 commercial titles were released for this computer). A total of 4 million C-128 were sold.

In late 80s two more computers would occupy a significant share of the market before the PC took over in the 90s; the Atari ST and the Commodore Amiga.

The Amiga was released in 1987 with the Amiga 500 model, it was considered as a spiritual succesor of the C-64 and was available in mass retail outlets. It came with a 7.15909 MHz Motorolla 68000 microprocessor, 512 KB of Chip RAM and a maximum capacity of 9.5KB, One double-density 3.5'' floppy drive which could read 720 KB IBM-PC disks and 880 kB standard Amiga disks. But what made this computer especial was its graphics capabilities; with a maximum of 640 × 256 and 4096 colors. It had its keyboard integrated with the CPU unit just like the C-64 and C-128, but unlike its predecessors the floppy disk drive was also integrated. Despite the Motorola 68000 was 32-bit internally the computer had a 16-bit data bus and 24-bit address bus. The Amiga 500 was mostly used for gaming and graphic edition.

The Atari ST was released in 1985 and was the biggest competitor of the Amiga and Macintosh. Just like the other two it came with a Motorola 68000 microprocessor, with 512 KB of RAM and a maximum of 4MB, 3 1/2" double-sided double-density floppy disks as storage (nominally 720 KB). It also featured a GUI.

So the Commodore 64, Commodore 128, Spectrum, Commodore Amiga and Atari ST were the most popular computers used by early Millennial children, mostly for gaming; but during their adolescence in the 90s they would move to the PC. With the mass introduction of Internet to the general public in the 90s and the big production of titles for PC, late Millennials would enter the computers world during their childhood using PCs, which by that time became the most popular system model up to our days. By the time early Millennials became young adults and entered the labor market and late Millennials entered the adolescence in the 2000s, Internet was a widespread technology and almost 50% of all the households in developed economies had at least one personal computer.

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