Historically, while much more cost effective than SRAM per Megabit, traditional DRAM has always suffered speed and latency penalties making it unsuitable for some applications. Consequently, product manufacturers have often been forced to opt … [Read more...]

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 2 GOPs, it is clear that their external … [Read more...]

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 small circuit board designed to accommodate … [Read more...]

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 industry. DIMMs have 168 … [Read more...]

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 and fit within the same board area … [Read more...]

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 of relaying the required information by using a … [Read more...]

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 chips in that memory bank. If the predicted value of … [Read more...]

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 for 32-bit words and eight for 64-bit … [Read more...]

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 an upgrade is therefore to determine what memory … [Read more...]

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 gradual and orderly transition to Synchronous DRAM … [Read more...]