I worked at The Computer Museum in Boston (RIP) in the '90s. We had an old computer whose boot program was a 2D array of toggle switches. In other words, it was

I worked at The Computer Museum in Boston (RIP) in the '90s. We had an old computer whose boot program was a 2D array of toggle switches. In other words, it was a small physical-write, electrical-read memory. I'm guessing it was about 16 switches wide by 30 switches high.