This document summarizes different types of semiconductor memory, including dynamic RAM (DRAM), static RAM (SRAM), read-only memory (ROM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), RAMBUS RAM, cache DRAM, and error correction techniques. It describes the basic structure and operation of DRAM and SRAM memory cells, as well as advanced organizations like SDRAM that can improve memory performance.