Short answers, pulled from the story.
A personal computer, or PC, is a computer designed for personal use and meant to be operated directly by an end user rather than a computer expert, administrator, company, or technician. It is typically used for word processing, internet browsing, email, multimedia playback, and gaming. Unlike minicomputers and mainframes, it does not use time-sharing by many people at once.
The Altair 8800, created by Micro Instrumentation and Telemetry Systems in 1974, is considered by many to be the first true personal computer. Based on the 8-bit Intel 8080 microprocessor, it is widely recognized as the first commercially successful personal computer and the spark of the microcomputer revolution. PC Magazine separately designated the 1973 IBM SCAMP prototype the world's first personal computer.
IBM's first PC, the IBM 5150, was introduced on the 12th of August 1981 at a price of US$1,565. It used the 5 megahertz Intel 8088 chip, ran a Microsoft-produced operating system later dubbed MS-DOS, and came with EasyWriter and VisiCalc preinstalled.
Federico Faggin developed the first single-chip microprocessor, the Intel 4004, in 1971, using silicon-gate MOS technology he had developed at Fairchild in 1968. Widespread commercial availability of microprocessors from the mid-1970s onward made computers cheap enough for small businesses and individuals to own.
Worldwide PC sales began to fall by 2013 as many consumers moved to tablets and smartphones. The first quarter of 2013 saw a 14% year-over-year decline, the largest on record since IDC began tracking in 1994, with Windows 8 cited as a contributing factor. One analyst said the market had reached the tipping point toward mobile computing.
The 1977 trinity refers to the Commodore PET, the Apple II, and the TRS-80 from Tandy Corporation. The Commodore PET was revealed in January 1977, the Apple II shipped on the 10th of June 1977, and the TRS-80 followed in August 1977 and sold over 100,000 units. The term was used especially in the North American market.