You could probably go all the way beck to the ancient abacus to show the evelution of PC's.  But we will stick to the 20th century.  If you were of age in the 60's, you will remember the keypunch cards that were used to store records.  It was a horrific job, entering records on a keypunch machine, which would punch small rectangular holes onto 3x6 cards which were stacked, and fed into a machine.  We've come a long way, baby.

There were two "ages" . . . development of large computers, done primarily by IBM - and then develpopment of microprocessors, done primarily by Intel, which finally allowed the manufacture of personal computers.

PHASE 1 - Computer Development

1944 - IBM Automatic Sequence Controlled Calculator, also called the Mark I - was completed in 1944 after six years of development with Harvard University. It was the first machine that could execute long computations automatically. Over 50 feet long, 8 feet high, and weighing almost 5 tons, the Mark I took less than a second to solve an addition problem, but about six seconds for multiplication and twice as long for division -- far slower than any pocket calculator today.

 

1952 - IBM 701 - its first large computer based on the vacuum tube. The tubes were quicker, smaller, and more easily replaceable than the electromechanical switches in the Mark I. The 701 executed 17,000 instructions per second and was used primarily for government and research work. But vacuum tubes rapidly moved computers into business applications such as billing, payroll and inventory control.

 

1959 IBM 7090 - one of the first fully transistorized mainframes, could perform 229,000 calculations per second. The Air Force used the 7090 to run its Ballistic Missile Early Warning System. In 1964, American Airlines' SABRE reservations system used two 7090 mainframes to link sales desks in 65 cities.

 

1964 IBM System/360 - the first large "family" of computers to use interchangeable software and peripheral equipment. Rather than purchase a new system when the need and budget grew, customers now could simply upgrade parts of their hardware. It was a bold departure from the monolithic, one-size-fits-all mainframe. Fortune magazine dubbed it "IBM's $5 billion gamble."  System/360 offered a choice of five processors and 19 combinations of power, speed and memory. A user could operate the same magnetic tape and disk products as another user with a processor 100 times more powerful. System/360 also offered dramatic performance gains, thanks to Solid Logic Technology (SLT) -- half-inch ceramic modules containing circuitry far denser, faster and more reliable than earlier transistors.

PHASE 2 - Microprocessor Development

1971:  The 4004 - This was Intel's first microprocessor. This breakthrough invention powered the Busicom calculator and paved the way for embedding intelligence in inanimate objects as well as the personal computer. 

1972: 8008 -  The 8008 was twice as powerful as the 4004.  According to the magazine Radio Electronics, Don Lancaster, a dedicated computer hobbyist, used the 8008 to create a predecessor to the first personal computer, a device Radio Electronics dubbed a "TV typewriter." It was used as a dumb terminal.

1974: 8080 - The 8080 became the brains of the first personal computer--the Altair, allegedly named for a destination of the Starship Enterprise from the Star Trek television show. Computer hobbyists could purchase a kit for the Altair for $395. Within months, it sold tens of thousands, creating the first PC back orders in history. 

1978: 8086-8088 - The basis for the classic old "PCjr, AT, and XT" computers - a pivotal sale to IBM's new personal computer division made the 8088 the brains of IBM's new hit product--the IBM PC.  

1982: 286 - the 286, also known as the 80286, was the first Intel processor that could run all the software written for its predecessor. This software compatibility remains a hallmark of Intel's family of microprocessors. Within 6 years of it release, there were an estimated 15 million 286-based personal computers installed around the world. 

1985: Intel 386 - The Intel 386TM microprocessor featured 275,000 transistors--more than 100times as many as the original 4004. It was a 32-bit chip and was "multi tasking," meaning it could run multiple programs at the same time. 

1989: Intel 486(TM) DX - The 486TM generation really meant you go from a command-level computer into point-and-click computing. I could have a color computer for the first time and do desktop publishing at a significant speed," recalls technology historian David K. Allison of the Smithsonian's National Museum of American History. The Intel 486TM processor was the first to offer a built-in math coprocessor, which speeds up computing because it offers complex math functions from the central processor. 

1993: Pentium - The PentiumŪ processor allowed computers to more easily incorporate "real world" data such as speech, sound, handwriting and photographic images. The name PentiumŪ, mentioned in the comics and on television talk shows, became a household word soon after introduction. 

1995: Pentium Pro - Released in the fall of 1995 the PentiumŪ Pro processor was designed to fuel 32-bit server and workstation-level applications, enabling fast computer-aided design, mechanical engineering and scientific computation. Each PentiumŪ Pro processor is packaged together with a second speed-enhancing cache memory chip. The powerful PentiumŪ Pro processor boasts 5.5 million transistors, which caused it to run hot.  So hot, that a huge heat sink was developed specifically for this CPU. 

1997: Pentium II  - The 7.5 million-transistor PentiumŪ II processor incorporates Intel MMXTM technology, which is designed specifically to process video, audio and graphics data efficiently. It was introduced in innovative Single Edge Contact (S.E.C) Cartridge that also incorporated a high-speed cache memory chip. With this chip, PC users can capture, edit and share digital photos with friends and family via the Internet; edit and add text, music or between-scene transitions to home movies; and, with a video phone, send video over standard phone lines and the Internet. 

1998: Pentium II  Xeon - The PentiumŪ II XeonTM processors are designed to meet the performance requirements of mid-range and higher servers and workstations. Consistent with Intel's strategy to deliver unique processor products targeted for specific markets segments, the PentiumŪ II XeonTM processors feature technical innovations specifically designed for workstations and servers that utilize demanding business applications such as Internet services, corporate data warehousing, digital content creation, and electronic and mechanical design automation. Systems based on the processor can be configured to scale to four or eight processors and beyond. 

1999: Celeron - Continuing Intel's strategy of developing processors for specific market segments, the Intel CeleronTM processor is designed for the Value PC market segment. It provides consumers great performance at an exceptional value, and it delivers excellent performance for uses such as gaming and educational software. 

1999: Pentium III - The PentiumŪ III processor features 70 new instructions--Internet Streaming SIMD extensions- that dramatically enhance the performance of advanced imaging, 3-D, streaming audio, video and speech recognition applications. It was designed to significantly enhance Internet experiences, allowing users to do such things as browse through realistic online museums and stores and download high-quality video. The processor incorporates 9.5 million transistors, and was introduced using 0.25-micron technology. 

1999: PentiumŪ III Xeon - The PentiumŪ III XeonTM processor extends Intel's offerings to the workstation and server market segments, providing additional performance for e-Commerce applications and advanced business computing. The processors incorporate the PentiumŪ III processor's 70 SIMD instructions, which enhance multimedia and streaming video applications. The PentiumŪ III XeonTM processor's advance cache technology speeds information from the system bus to the processor, significantly boosting performance. It is designed for systems with multiprocessor configurations.