When was the first computer invented?

When was the first computer invented?

Unfortunately this question has no easy answer because of all the different types of classifications and types of computers. Therefore this document has been created with a listing of each of the first computers starting with the first programmable computer leading up to the computers of today. Keep in mind that early inventions such as the abacus, calculators, tablet machines, difference machine, etc. are not accounted for in this document.
First programmable computer

The Z1 originally created by Germany's Konrad Zuse in his parents living room in 1936 to 1938 is considered to be the first electrical binary programmable computer.
See our Z1 dictionary definition for additional information about this computer.
The first digital computer

Short for Atanasoff-Berry Computer, the ABC started being developed by Professor John Vincent Atanasoff and graduate student Cliff Berry in 1937 and continued to be developed until 1942 at the Iowa State College (now Iowa State University). On October 19, 1973, US Federal Judge Earl R. Larson signed his decision that the ENIAC patent by Eckert and Mauchly was invalid and named Atanasoff the inventor of the electronic digital computer.
See our ABC dictionary definition for additional information about this computer.
The ENIAC was invented by J. Presper Eckert and John Mauchly at the University of Pennsylvania and began construction in 1943 and was not completed until 1946. It occupied about 1,800 square feet and used about 18,000 vacuum tubes, weighing almost 50 tons. Although the Judge ruled that the ABC computer was the first digital computer many still consider the ENIAC to be the first digital computer.
See our ENIAC dictionary definition for additional information about this computer.
Because of the Judge ruling and because the case was never appealed like most we consider the ABC to be the first digital computer. However, because the ABC was never fully functional we consider the first functional digital computer to be the ENIAC.
The first transistor computer

The TX-O (Transistorized Experimental computer) and first transistorized computer is demonstrated at the Massachusetts Institute of Technology in 1956.
The first stored program computer
The early British computer known as the EDSAC is considered to be the first stored program electronic computer. The computer performed its first calculation on May 6, 1949 and was the computer that ran the first graphical computer game.
See our EDSAC dictionary definition for additional information about this computer.
The first minicomputer

In 1960 Digital Equipment Corporation released its first of many PDP computers the PDP-
The first personal computer
In 1975 Ed Roberts coined the term personal computer when he introduced the Altair 8800. Although the first personal computer is considered to be the Kenback-1, which was first introduced for $750 in 1971. The computer relied on a series of switches for inputting data and output data by turning on and off a series of lights.
The Micral is considered the be the first commercial non-assembly computer. The computer used the Intel 8008 processor and sold for $1,750 in 1973.
The first workstation

Although never sold the first workstation is considered to be the Xerox Alto, introduced in 1974. The computer was revolutionary for its time and included a fully functional computer, display, and mouse. The computer operated like many computers today utilizing windows, menus and icons as an interface to its operating system.
The first laptop or portable computer
The first portable computer or laptop is considered to be the Osborne I, a portable computer developed by Adam Osborne that weighed 24 pounds, a 5-inch display, 64 KB of memory, two 5 1/4" floppy drives, and a modem.
IBM PCD later released the IBM portable in 1984, it's first portable computer that weighed in at 30 pounds. IBM PCD later announced in 1986 it's first laptop computer, the PC Convertible, weighing 12 pounds. And in 1994 introduces the IBM ThinkPad 775CD, the first notebook with an integrated CD-ROM.