Conventional DRAM architectures have reached their practical upper limit in operating frequency and bus width. With mass market CPUs operating at over 300MHz and media processors executing more than … [Continue reading]
Direct DRAM
SIMMs
Memory chips are generally packaged into small plastic or ceramic dual inline packages (DIPs) which are themselves assembled into a memory module. The single inline memory module or SIMM is a … [Continue reading]
DIMM Memory – Computer Memory – Definition
By the end of the millennium, as memory subsystems standardised around an 8-byte data interface, the Dual In-line Memory Module (DIMM) had replaced the SIMM as the module standard for the PC … [Continue reading]
RIMMs Memory
With the introduction of Direct RDRAM (DRDRAM) in 1999 came the RIMM module (the name is not an acronym, but a trademark of Rambus Inc.). RIMM connectors have a form factor similar to DIMMs … [Continue reading]
Memory Presence Detection
When a computer system boots up, it must detect the configuration of the memory modules in order to run properly. For a number of years, Parallel Presence Detect (PPD) was the traditional method … [Continue reading]
Parity Memory
Memory modules have traditionally been available in two basic flavours: non-parity and parity. Parity checking uses a ninth memory chip to hold checksum data on the contents of the other eight … [Continue reading]
ECC Memory
Unlike parity memory, which uses a single bit to provide protection to eight bits, ECC uses larger groupings. Five ECC bits are needed to protect each eight-bit word, six for 16-bit words, seven … [Continue reading]
Memory Upgrades
In recent times, as well as becoming much cheaper, RAM has also become more complicated. There are currently a proliferation of different varieties, shapes and voltages. The first step in planning … [Continue reading]
The Evolution of Memory
In the late 1990s, PC users have benefited from an extremely stable period in the evolution of memory architecture. Since the poorly organised transition from FPM to EDO there has been a … [Continue reading]
Flash Memory
Flash memory is a solid-state, non-volatile, rewritable memory that works like RAM and a hard-disk drive combined. It resembles conventional memory, coming in the form of discrete chips, modules, or memory cards such as those made by Memory … [Continue reading]