Describe early computers in term of size and what they could do?

Answer 1

They were huge, in 1950 it was the size of a room. They started out like calculators, doing math equations.

The very first computers were used in England in the 40s to break German codes and ciphers. Alan Turing and John von Neuman worked on this project that for some strange reason remained secret until long after the war. Thus it got forgotten as the cradle of real purposeful computing.

The first commercial computing was by a LEO computer which was operational in 1951. J Lyons & Co, a British baking and catering company decided in 1947 to help develop computers and use them for the management of ordering and supply to its chain of teashops. Lyons Electronic Office (LEO) was the result. At the end of 1953 a LEO computer took over payroll calculation at Lyons. The time to calculate one worker's pay fell from 8 minutes to one and half seconds for the first time anywhere.

See Wikipedia

LEO had 2K of 35 bit words and ran at 500 kHz

Answer 2

Early computers typically occupied a large room (at least 1000 sq. ft.), gave off enough heat from their tubes that they needed either an industrial air conditioner or refrigerated water cooling, or both. Typical instruction execution speeds peaked out at a couple thousand instructions per second (modern computers execute instructions from billions to trillions per second). The memory of early computers was between 400 characters to a few thousand characters. No external storage except punched cards or punched tape.

John von Neuman is said to have told a doctoral student who proposed writing an assembler for his IAS computer at Princeton, to make it easier to program, "Don't you dare. The computer's time is too valuable to waste on simple bookkeeping tasks like that that the programmers can easily handle." (IAS time cost something over $1000/hr, a typical graduate student programmer was almost free, even a paid programmer was likely making under $10/hr and that was considered very good money in those days)