Williams Tube (1947)

Sir Frederick Williams of Manchester University modified a cathode-ray tube to display dots and dashes which represented binary ones and zeros. The IBM 701 and other vacuum tube computers used the Williams tube for memory.

Mark I computer, a two year building project, filled a medium-sized room. It composed of 1,300 vacuum tubes. Paper tape, switches and a teleprinter were the mediums of input and output.

UNIVAC I, the first commercial computer was available for purchase. Its memory device was called a mercury delay line. A tube of mercury, about 30 feet long, was curled around the inside of the UNIVAC. Electrical pulses sent through the mercury at the "write gates" would input data to the "read gates" to store information.

IBM 1400 Series (1961)

The 1401 mainframe, the first in the 1400 series, used transistors instead of vacuum tubes, and had a magnetic core memory. More than 12,000 of the 1401 computers were sold.

Nova (1968)

The Nova minicomputer had 32 kilobytes of memory, and sold for $8,000.

Kenbak-1 (1971)

The Kenbak-1, considered the first personal computer, used integrated circuits. Switches performed the input, and lights displayed the output. It had 256 bytes of memory. It's price was about $750. After only 40 machines were sold in two years, the Kenbak-I was discontinued.

Scelbi 8H (1974)

Scelbi's 8H computer, was based on Intel's 8008 microprocessor. The computer was available both in kit form and fully assembled. It had 4 kilobytes of internal memory and a cassette tape. It came with both teletype and oscilloscope interfaces. Just one year later, Scelbi came out with 8B, which had 16 kilobytes. The company sold about 200 machines, and lost $500 per unit.

The Altair 8800 computer kit, based on Intel's 8080 microprocessor, had 256 bytes of memory (expandable to 64K) and an open 100-line bus structure that evolved into the S-100 standard. The manufacturing company, MITS, sold many machines, at a price of $297 or $395 with a case. Bill Gates and Paul Allen licensed BASIC as the software language for the Altair. This machine was produced for about three years.

Visual Display Module (1975)

The visual display module (VDM) prototype was a memory-mapped alphanumeric video display for personal computers. The visual display module allowed use of personal computers for interactive games.

The Cray I, considered the first commercially successful vector processor, was the fastest machine of its time. Its C shape shortened the wires, lessening the time for signals to travel them. Its speed was 166 million floating-point operations per second. It is 56 cubic feet in size, and weighs 5,300 pounds. It's made using integrated circuits.

The Commodore Personal Electronic Transactor came fully assembled, with two built-in cassette drives and a keyboard. It was considered easy to operate, and had a choice of 4 or 8 kilobytes of memory.

The Apple II came with a printed circuit, motherboard, switching power supply keyboard, case assembly, manual, joystick, A/C power cord, and cassette tape drive. Even though it did not include a monitor, it could be connected to a television set. It had 16 K of memory.

TRS-80 (1977)

Tandy Radio Shack's first desktop computer cost $599.95. 10,000 machines were sold in one year, far better than predicted 3,000. The TRS-80 was based on the Z80 microprocessor, had 4 KB of memory, and cassette storage. It came with video display, the language BASIC, and well written manuals.

The VAX 11/780, made by Digital Equipment Corp., had 4.3 gigabytes of virtual memory, much more than the minicomputers of its time.

Osborne I, created by Adam Osborne, was the first portable computer. It weighed 24 pounds, and could fit under an airplane seat. It had a low price of $1,795, considering it came with software worth almost $1,500. It had 64 KB of memory, and two 5 1/4 inch floppy disk drives. The screen's size seemed to be the only downfall, at 5-inches.

Lisa was the first personal computer with a graphical user interface. It was based on Motorola's 68000 microprocessor. It came with 1 MB of Random Access Memory, a 12 inch monochrome monitor, two 5 1/4 in floppy disk drives, and a 5MB hard drive. The Lisa was too expensive, at $10,000, for success.

The Connection Machine was a big advance in artificial intelligence. It could complete several billion operations per second. Each of 16,000 processors had its own memory linked with others. The way the processors could work together was a key point in the high artificial intelligence of the machine.