Mainframe Computers History

Mainframe computers - The ENIAC story

ENIAC, which is short for Electronic Numerical Integrator and Computer, was the first mainframe computer conceived and designed by John Mauchly and J. Presper Eckert who worked at the University of Pennsylvania.

(U.S. Army photo from the archives of the ARL Technical Library)

They developed it for the U.S. Army's Ballistic Research Laboratory who needed a better way for gunners to quickly look up which settings to use with a particular weapon, and under particular conditions.

So the ENIAC was built to calculate artillery firing tables.

The machine was completed on February 14, 1946 and was in operation till October 2, 1955, with a slight pause in November 9, 1946 for a refurbishment.

(U.S. Army photo from the archives of the ARL Technical Library)

Some Fascinating facts:

• Cost - almost $500,000
• contained 17,468 vacuum tubes
• 7,200 crystal diodes,
• 1,500 relays,
• 70,000 resistors,
• 10,000 capacitors
• 6,000 manual switches
• 5 million hand-soldered joints
• It weighed 30 short tons
• was roughly 8.5 feet height by 3 feet by 80 feet width
• took up 680 square feet
• consumed 150 kW of energy consumption
• could execute 5,000 additions, 357 multiplications, and 38 divisions in one second
• The basic machine cycle was 200 microseconds (20 cycles of the 100 kHz clock in the cycling unit), or 5,000 cycles per second for operations on the 10-digit numbers.
  

(U.S. Army photo from the archives of the ARL Technical Library)

The programmers

Input into this monster was made by an IBM card reader and output by an IBM card punch. The programming was quite complex. The programmers would figure it out on paper first and then manipulate the machines switches and cables to get it into the machine. The programming was done mostly by a team of 6 women.

• Kay McNulty
• Betty Jennings
• Betty Snyder
• Marlyn Wescoff
• Fran Bilas
• Ruth Lichterman

In 1997 these women were inducted into the Women in Technology International Hall of Fame.

(U.S. Army photo from the archives of the ARL Technical Library)

Mainframe computers - The EDVAC story

The EDVAC was designed by the same two designers who designed the ENIAC as we discussed above. EDVAC is short for Electronic Discrete Variable Automatic Computer. It used binary rather than decimal and was a stored program machine.

The EDVAC came about to share the workload with the EDVAC. Because it employed newer technologies, it was faster and more cost effective which rendered the ENIAC obsolute.

(U.S. Army photo from the archives of the ARL Technical Library)

Mainframe computers - The ORDAC story

The ORDVAC which is short for Ordinance Discrete Variable Automatic Computer, was another computer of that era build for the US Military. The ORDVAC was the first computer to have a compiler and it was used to perform ballistic trajectory calculations.

"Mainframe Computers History" To More Computer History