๐ ๐ฎ๐ด๐ป๐ฒ๐๐ถ๐ฐ ๐๐ผ๐ฟ๐ฒ ๐ ๐ฒ๐บ๐ผ๐ฟ๐ ๐๐ ๐ฝ๐น๐ฎ๐ถ๐ป๐ฒ๐ฑ
You have 64GB or 128GB of RAM today. You complain when apps slow down. Memory used to be different. It was not silicon. It was hand-woven.
Magnetic core memory ruled from the 1950s to the 1970s. It used tiny ferrite rings. Each ring held one bit of data.
The rings are donut-shaped. This shape keeps the magnetic field inside. A ring faces clockwise for 0 or counter-clockwise for 1.
Each core uses four wires:
- X-Select: Horizontal.
- Y-Select: Vertical.
- Sense: Detects state changes.
- Inhibit: Stops writes.
Reading a bit flips the ring to 0. If the ring was 1, the sense wire feels a pulse. If the ring was 0, nothing happens.
Reading erases the data. You must rewrite the bit immediately. This made core memory slow.
Workers wove thousands of these wires by hand. Every bend had to be perfect.
Be glad you use silicon. You do not have to debug hand-woven donuts. Modern RAM sits on the work of these engineers.