2016•Unpublished venueRequires access
Electronic Memory
Eben Upton, Jeff Duntemann, Ralph J. Roberts, Tim Mamtora, Ben Everard
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Abstract
In executing instructions, the central processing unit (CPU) reads data from memory, changes it and then writes it back. Data and instructions that are used a lot are pulled in closer, via cache. The designs of CPUs are heavily influenced by the speed limitations of system memory. Magnetic tape was a faster storage medium than paper tape and cards, and it had the advantage of being rewritable. Like both core memory and Static Random Access Memory (SRAM), Dynamic Random Access Memory (DRAM) memory chips are based on two-dimensional arrays of memory cells. This chapter looks at a very simple memory chip and how it works internally. It talks about combining memory chips into memory systems and explains how DRAM and SRAM work. For desktop and conventional laptop computers, multiple chips are assembled onto small “stick” printed circuit modules. Until the late 1990s these were single in-line memory modules (SIMMs).