RAM is born - Magnetic Core that is.

[Analog]

Back when computers still weighed hundreds of pounds and were primarily used by the military, computer memory relied on cathode rays to retrieve information. But the Navy needed a faster computer that could run flight simulations in real time.


In stepped a team at the Massachusetts Institute of Technology. Led by professor Jay Forrester, the researchers developed a three-dimensional magnetic structure code-named Project Whirlwind.


The structure consisted of a plane made of wires and magnetic rings called cores. Each ring contained one bit of data. Every bit on the memory plane could be accessed with a single read-and-write cycle.


In short, magnetic core memory was the first random access memory that was practical, reliable and relatively high-speed. The time it took to request and retrieve information from memory was a microsecond — hundreds of thousands of times slower than memory today, but nonetheless a magnificent achievement in the 1950s.


“When we were working on this, in a million years we couldn’t imagine what would happen with memory,” said Bernard Widrow, who worked on Project Whirlwind with Forrester, in a 2009 interview with Edison Tech Center.
Forrester applied for a patent on his invention May 11, 1951. Project Whirlwind stayed active until 1959, though the technology was never used for a flight simulator.

http://www.wired.com/thisdayintech/2010/05/0511magnetic-core-memory#ixzz0nadqzOgc
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[AndroidVageta]

Wow...that is totally crazy...to think, 1 bit per core...4GB of this shit would be like state sized!

 

[Paperdoc]

When I was in university in the late 1960's the place's mainframe system was an IBM model 360 / 50, with 256 KB of RAM of this type - ferrite rings on a wire grid. It was called "core" memory from the fact that magnetically succeptible metal was the common "core" material in transformers and inductor coils in electronic circuits. A little later at significant expense it was doubled to 512 KB of RAM. Each ring has three wires running through it. To write to one memory location (ring) the circuit had to fire pulses of current through two perpendicular wires, thus setting its magnetic direction. To read, it fired a similar current pulse through two wires, and watched the output current pulse from the third wire. If the magnetic bit already was set to that direction, there would be no change and the third-wire signal would be nothing. But if the read pulse caused a magnetic reversal, the third wire would output a current pulse. Thus the ring was "read". AND, if the pulse was output, this indicated that it had been changed, so the operation had to go back and re-set the location to its original state so the data were not altered by the read operation.

Like most computer systems then and now, main memory actually was on magnetic disks and tapes. Tapes were the high-volume medium - they were about 1" wide and carried about 10 tracks of information as parallel bytes - 8 data bits plus parity and timing signal tracks. The tape drives are the large cabinets one sees in older depictions of computer mainframe systems - about 6 feet high by 3 feet wide, with two reels of tape spinning at the top front.

The magnetic disk packs they used were unlike today's HDD's. They were a vertical axle about 10" tall with about 8 to 10 disks attached to them and completely open to air - no sealed package. Each disk was about 12" diameter like an old vinyl LP, but rigid with magnetic coating on it. Each disk pack was stored in a case to keep it protected and clean, and could be removed and loaded into the disk player unit without touching surfaces. The player unit was top-loading. The multiple heads were all mounted on one arm mechanism with rigid arms that positioned the heads a small distance from the disk surfaces. They were NOT Winchester designs. (Winchester is the basis of modern hard drives, in which the head suspension is flexible and the heads are lifted off the disk surfaces by the flow of air at the disk surface as it turns.) The computer center operators would mount any necessary disk packs or tapes in the appropriate drives as required by the notes on written forms accompanying the jobs submitted on punched cards, and also contained in the Job Control cards at the beginning of the stack.