I have an 8K core memory board hanging on my office wall, once belonging to a DEC something or another, just below a couple of (very old) Marconi Wireless Telegraph Company stock certificates. There was a story floating around Control Data's early days about its core memory and how the tiny magnetic donuts were hand threaded in Hong Kong because the process needed the fine and delicate hands of Asian women. The location was affectionately known as "Bill Norris' Far East Core House"!
My favorite historical memory device is the Univac FASTRAND moving head magnetic drum unit, which stored data on the surface of a heavy drum approx 6 feet long by 1 foot in diameter. The Devil's DP Dictionary defined it as "a device for storing angular momentum". The gyroscopic effect of the drum was so strong they had to add a counter-rotating drum so that the 4,500-pound unit wouldn't turn as the Earth rotated.
OK, I can beat you all. My first computer, a Sinclair ZX81 (used to be called Timex in the states) had just 1K of RAM.
I'll see your Sinclair and raise you by an Elf. I built my first computer based around the design for the RCA 1802 Cosmac Elf. It had 256 bytes of CMOS memory and that consisted of 2 chips! When I developed our first product I used a 1K x8 bipolar PROM that I turned on and off to conserve power, and after partioning the software functionality paged in ~200 bytes ar a time (needed scratchpad,stack etc in the rest).