You’ve heard of DRAM, HBM, probably SRAM, but RDRAM…now that was a weird one. Famously used in the Sony PS2, its RDRAM had ~3x the bandwidth of your typical high end PC. If you want more memory bandwidth in a dense die, there’s (roughly) two things you can do. You can *add* many more wires (wide+close, like hbm). Or, you can make the wires *faster* and use less of them (narrow). Rambus, the creator of RDRAM, took the second bet. It was quite contrarian, but garnered some attention from Intel as well. The main issue, among others, is that RDRAM was expensive, AND high latency. For typical PC-style workloads, random access latency dominates, so it was a tough sell. Although the PS2 was a roaring success (high-bw streaming workloads made sense), it barely lasted ~3 years in the PC market. Like many ideas, Rambus+RDRAM was arguably just way, way too early. Today, CXL memory uses many of the same initial principles! If you think about a pin-efficient, high speed link, over longer distances…well, that’s kinda just CXL. Funnily enough, Rambus still exists, and is heavily involved in CXL memory controller IP these days!