Recently the computer was ordered to calculate the cubes of all numbers from one through 2,000. The machine had the answers in two seconds. But it took an hour and a quarter for the teletypewriter linked to the machine to tap out the numbers--1, 8, 27, 64, 125, 216, etc., until it reached 8,000,000,000. The teletype machine is limited to one five strokes a second.
In thirty-six millionths a second the "brain" can recall any of the 1,024 numbers it retains. In one-thousandth of a second It can multiply a twelve-digit number by another with the same number of figures. The machine employs the binary system--which uses only 0 and 1 to translate decimal system numbers of 0 to 9--so the twelve-digit numbers become thirty-nine digit numbers.
Next month the computer is to be turned over the Army's Ballistic Research Laboratories at Aberdeen (Md.) Provlng Grounds. There the Army will use it for preparing gunfire tables and solving other complicated mathematical problems.
A twin machine now under construction will be completed in June.
The computer, under construction since l949, is being tested for sixteen hours daily. A team of Army Ordnance experts poses military problems to the machine for eight hours. University scientists then take over with academic questions.
Named the Ordnance Variable Automatic Computer, the "brain" is more frequently called ORDVAC. Another ORDVAC-type machine is now under construction at the Institute of Advanced Study at Princeton, N.J., where fundamental work dealing with this type of computer was originally carried out by Prof. John von Neumann and co-workers.
The secret of ORDVACs memory lies lies in forty of the 2,720 vacum tubes in a cabinet ten feet long and two feet wide and and eight and one-halr feet high. Similar to the picture tube in a television set, the cathode-ray memory tubes only three inches in diameter. Each tube can record 1,024 digits, arranged in a square thirty-two dots high and thirty-two dots wide.
Despite its complicated interior, ORDVAC is like other computers in its insistence on simply recorded data. A particular bit of information fed into computer may be expressed as 0 or 1.
The varying charges are beamed at the proper dots on the face of the memory tube. As the machine operates, the "memory" appears as glowing green dots on the face of the tube.
The 0 and 1 can be used to record any number. For example: 10 times 142 (decimal system) is written as 1010 times l0001110(binary)
The ORDVAC with its electronic memory tubes is 100 times faster than some computing machines which use magnetic drums as memory elements. It is five times faster than calculators which use mercury memory storage elements.
Two machines with memories of the ORDVAC type are being used by the Bureau of Standards but each stores only 512 digits a tube as compared with ORDVAC's 1,024.