- Jan 1948
- Wallace Eckert (1902-1971, no relation to Presper Eckert and not
mentioned again in this article) of IBM, with his team, completes
the "SSEC" ("Selective Sequence Electronic Calculator"). This technological
hybrid has vacuum tube logic with 8 20-digit registers, 150 20-digit words
of relay memory, and a program that is partly stored but also controlled
by a plugboard. IBM considers it the first computer.
- Jun 1948
- Max Newman, F. C. Williams, and their team at Manchester University,
Manchester, England, complete a prototype machine called the
"Mark I". This is the first machine that everyone would call a computer,
because it's the first with a true stored-program capability.
It uses a new type of memory invented by Williams, which uses the
residual charges left on the screen of a CRT after the electron beam has been
fired at it. (The bits are read by firing another beam through them and
reading the voltage at an electrode beyond the screen.) This is a bit
unreliable but is fast, relatively cheap, and much more compact (with room
for about 1024 or 2048 bits per tube) than any other memory then existing.
The Mark I uses six of them, but I don't know of how many bits.
Its programs are initially entered in binary on a keyboard, and
the output is read in binary from another CRT. Later Turing joins the
team and devises a primitive form of assembly language, one of several
developed in different places.
Newman was the first person shown Turing's 1937 paper in draft form.