I came across this plate of ancient (circa 1960-1970) computer memory. This is the earliest form of memory using magnetic core. The size of this plate is about 8 inch x 6 inch.
What you see is an array of tiny wires and circular magnetic core which is invisible under the naked eyes.
However, I took a closeup photo and amplify it and the circular magnetic core became visible. Click on the above to see an enlarged picture. The magnetic cores are black circular tiny rings which like donuts. Each of the above is 32x64 bits, ie, 256 bytes. On the plate, there are 18 such blocks. It seems that it is for 16bits CPU with 2 bits for error correction, etc.
It was made in USA. Cost? No idea.... must be US$1000s.
Compare this with a 1999 IBM RAM stick, each of 256MB. When it was first purchased, I think they cost the price of a detached house in Miri! Now, it cost less than US$20 per stick.
This memory board has 32KB of RAM. I assemble it myself for my single board microprocessor. It was in 1979 and cost around RM300. The computer can only program in assembly language or machine code or single BASIC.
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