RAM Module Types

The two types differ in the technology they use to hold data, dynamic Dynamic in this context means 'changing', or 'constantly current'. Dynamic data must be constantly refreshed to keep up with on-going changes, while 'static' data remains constant for fixed periods, say daily or weekly updates.RAM Short for Random Access Memory, RAM is memory chips used to temporarily store data until needed by the CPU. RAM is located on a direct path to the CPU and is electrical (vice mechanical), so data held in RAM can be accessed much faster than data stored on the hard disk (a mechanical device). being the more common for main memory.

 

Dynamic RAM (DRAM) needs to be refreshed thousands of times per second.

 

Static RAM (SRAM) does not need to be refreshed, which makes it faster; but it is also more expensive than dynamic RAM.

 

Both types of RAM are volatile, meaning that they lose their contents when the power is turned off.

 

SIMMs plug into long matching sockets on the motherboard The motherboard is the 'base' into which other components are plugged. Made of a non-conductive material into which conductive circuits are 'sandwiched'. These circuits carry data from one component to another. The circuits are called 'printed circuits' because they are so thin they appear to be 'printed' on the surface. . Physically, SIMMs have either 30, or 72 pins, and normally contain 8 RAM chips per module.

 

The 30 pin SIMM Short for Single Inline Memory Module, SIMM is a RAM configuration. The 30 pin SIMM is an older format that is available in RAM capacities from 256 kilobytes,to 1, 2, or 4 megabytes. The 72 pin SIMMs are available in larger capacities, typically1, 2, 4, 8, 16, 32 (and higher) megabyte sizes. is an older format that is available in RAM capacities from 256 kilobytes, to 1, 2, or 4 megabytes. The 72 pin SIMMs are available in larger capacities, typically 1, 2, 4, 8, 16, 32 (and higher) megabyte Approximately one million 'bytes'. In binary counting it is 2 to the 20th power, or 1,048,576. In decimal counting, it is a nice, round 'one million' bytes. A 'byte' is equal to 8 'bits', and is used to roughly describe the amount of binary data required to represent a single unformatted keyboard character. sizes.

 

SIMM chips have been replaced by DIMM Short for Dual Inline Memory Module, a configuration for RAM chips. DIMMs look somewhat like two SIMMs glued back-to-back (but longer). They normally have 168 pins, and are available in capacities of 32 to 64 megabytes, and above. DIMM configurations are not 'paired' as are SIMM configurations. You may add, a single module, instead of pairs. chips in newer computers.

 

DIMMs look somewhat like two SIMMs glued back-to-back (but longer). They normally have 168 pins, and are available in capacities of 32 to 64 megabytes, and above.

 

DIMM configurations are not 'paired' as are SIMM configurations. This means that you may be able to replace, or add, a single module, instead of having to always 'balance' module additions in pairs. Check with your technician.

 

Either SIMMs or DIMMs may be constructed with either eight (8) or nine (9) chips on the module. Why have nine chips, when all memory seems to be divisible by the number eight? (Note the numbers above).

 

Because there are 'parity' and 'non-parity' modules. Both modules contain eight (8) chips that house the memory storage itself, but a parity module contains a ninth chip, whose job is to check the other eight chips for errors (called 'error-checking', of course).

 

Parity memory is more expensive than non-parity memory. Most newer PCs require parity memory. Check the documentation on your PC Short for 'Personal Computer'. The term 'PC' has come to be accepted as identifying a computer which uses the Microsoft 'Windows' operating system, as opposed to those computers that use other OSs such as 'Apple', 'Unix', 'Linux', or others. , or just log-on to the manufacturer's web site to see what you need when upgrading RAM.

 

RAM memory is speed-rated in 'nanoseconds', abbreviated 'ns'. A nanosecond is a billionth of a second. This is a measurement of how long it takes the memory to execute an instruction, so a lower number (60ns) is faster than a higher number (80ns). Of course, the higher speeds cost more. DRAM speed today approaches or exceeds System BUS A 'bus' is the group of wires, stamped conductors, and connectors that transfer data from one component to another. The 'System' bus' is part of the motherboard. All internal data flows through the system bus' to and from the CPU. Another bus type is the I/O, or 'external' bus. speed.

 

Some CPU Short for Central Processing Unit. Physically, the CPU is approximately 2 inches square, and 1/2 inch thick. It is a silicon wafer containing millions of transistors, each of which may be either 'on' or 'off'. The CPU plugs into the motherboard, and is the main processing component for the computer. Often referred to as the 'micro-processor'. manufacturers have designed their CPU to work best with their own proprietary (main memory) RAM design. Be careful, when selecting RAM, to mention the type of CPU you have. For instance, some AMD systems (American Micro Devices, a manufacturer of CPUs) use a proprietary RAM design called DDR, which is extremely fast.