The Atanasoff-Berry Computer was the world's first electronic digital computer. It was built by John Vincent Atanasoff and Clifford Berry at Iowa State University during 1937-42, but unfortunately because of the war they never finished it.
In 1939, Stibitz and S.B. Williams built the Complex Number Calculator, the world's first electrical digital computer. Its brain consisted of 450 telephone relays and 10 crossbar switches and it could find the quotient of two eight-place complex numbers in about 30 seconds. Three teletypewriters provided input to the machine.
In 1940, Stibitz took one of the teletypewriters to an American Mathematical Association meeting at Dartmouth, New Hampshire, and used it to communicate over phone lines with the Complex Number Calculator in New York. This was the world's first demonstration of remote computing.
The CNC, later renamed the Model 1 Relay Computer, remained in operation until 1949.
The ENIAC. The machine designed by Drs. Eckert and Mauchly was a monstrosity. When it was finished, the ENIAC filled an entire room, weighed thirty tons, and consumed two hundred kilowatts of power. It generated so much heat that it had to be placed in one of the few rooms at the University with a forced air cooling system. Vacuum tubes, over 19,000 of them, were the principal elements in the computer's circuitry. It also had fifteen hundred relays and hundreds of thousands of resistors, capacitors, and inductors. All of this electronics were held in forty-two panels nine feet tall, two feet wide, and one foot thick. They were arranged in a "U" shape, with three panels on wheels so they could be moved around.
Eckert and Mauchly went on to create EDIVAC, the first stored program computer. Last but not least, the first commercially available computer, the universal automatic computer (UNIVAC I), was also based on the EDVAC design. Work started on UNIVAC I in 1948, and the first unit was delivered in 1951, which therefore predates EDVAC's becoming fully operational.
1970 the first static and dynamic RAMs developed.
The first microprocessor, the 4004 was developed in 1971.
The 8008 microprocessor developed in 1972.
1973 the Xerox Alto computer.
1973 the Micral microcomputer.
1973 the Scelbi-8H microcomputer.
[This is probably where today began for PC's]
1974 the 8080 microcomputer developed.
1974 the 6800 microcomputer developed.
1975 MITS Altair 8800. Developed by Ed Roberts used Intel 8080 and was the first Microcomputer kit.
1975 IMSAI 8080. Developed Bill Millard. First Altair clone and Millard went on to found ComputerLand.
1975 IBM 5100. 16k storage, keyboard, CRT, BASIC, tape cartridge mass storage, $9,000 Assembled.
1977 Commodore PET. MOS 6502 chip, keyboard, tape drive & CRT, $595.
1977 Apple II, keyboard, cassette, game paddles, $1,298.
1977 TRS-80 Model 1, Developed by Radio Shack, Zilog Z-80 chip, $599.
1978 Atari 400. Best Graphics, $1,000.
1979 TI-99/A. TMS9900 16 bit processor, $1,150.
1980 Commodore VIC-20. Modem interface, ROM cartridge slot
$299.
1981 Osborne 1. First portable 5 inch display, Bundled software, $1,795.
1981 IBM PC. Intel 8088 chip, MS-DOS, $3,005
1982 Commodore 64. Microsoft BASIC, Non MS-DOS, $595.
1982 TRS-80 Model 100. Laptop portable, ROM software, 4 pounds, $800.
1983 Apple LISA. First commercial GUI, 5 meg hard drive
$9,995.
1983 HP-150. Intel 8086 chip, 3.5 inch floppy drive, touch screen interface, $3,995.
1984 Apple Macintosh. Motorola 68000 chip, $2,495.
1986 Compaq 386. Phoenix BIOS, First 386 based microcomputer, $6,500.
1987 NeXT. Developed by Steve Jobs, Motorola 68030, Magneto Optical Drive, Unix operating system with GUI, $10,000.
1989 Compaq Deskpro. 486 chip, tower system box server & desktop models, $13,999.
1994 DEC Alpha. DEC Alpha 64 bit RISC chip, Windows NT
$9,995.
1995 Micron Pro. Pentium Pro chip, Windows NT, $5,995.