RAM: the forgotten history (2024)

The piece argues that the defining breakthrough for modern computing was electronically-controlled working memory rather than early mechanical ideas, and that RAM constraints, not programmability per se, were the main bottleneck until late in the 20th century. It traces the first practical memories from electromechanical relays (used in Zuse’s Z3) and bistable vacuum-tube latches (Eccles and Jordan) to the logical SR latch architecture that underpins modern SRAM. Tubes and relays were too slow, bulky, and power-hungry for large main memory, so designers turned to dynamic schemes and other clever physical processes to keep data “in flight” cheaply.

The narrative follows dynamic solutions - Atanasoff-Berry capacitor drums as DRAM precursors that required refresh, acoustic delay lines including mercury columns and torsion-wire memory to store bits in propagating waves, and charge-storage CRT-like devices such as the Williams and Selectron tubes. It then covers magnetic memories: drums for intermediate latency and ferrite core arrays that used intersecting wires to flip cores and a destructive-read sensing pulse. The summary closes by noting that memory technology continued to evolve (for example, nonvolatile MRAM up to tens of megabytes) and that these shifts in memory design fundamentally shaped computer architecture and practical computing progress.