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Memory is what allows a computer to function in a timely fashion. With out memory a computer would be nothing more than a calculator. Memory is where the computer stores its current task at the time so it knows what it is doing. If there was no memory all of this data would have to be stored on the hard disk drive. Storing data on the hard disk drive for short-term use is not practical because it would be far to slow.
Memory works like any thing else in a computer using binary ones and zeros a representation of a high and low, on and off, a reflective surface or a dull surface. All of these are different ways of representing binary. The difference between memories is how it represents the ones and zeroes. Memory we have today uses many IC-chipsets (integrated circuit chipsets) on the memory board. Before we had memory with IC-chipsets we used simple transistor circuits. Before that was magnetic core memory. Magnetic core memory this memory was developed in the late 1940's it works by magnets and wire strung horizontally and vertically, with one wire going to the center to sense a charge or a lack of one that could be represented as a one or zero. This memory was used until the 1970's when randomly accessible memory came out. Before magnetic core memory they used delay line memory with tubes of mercury as a delay system. How this worked was that pulses of electricity where sent threw these tubes of mercury which would convert the electrical wave in to a physical wave on different millisecond delays to either be read as a one or a zero. After the pulses reached the end of their tubes they were converted back in to electric pulses, amplified, sharpened, and then introduced back in to the system thus clearing the memory. Before this there were other various delay devices used to performer the same results all of these types of memory were linear and were not able to be accessed randomly.
In the 1970's RAM (randomly accessible memory) type memory was being introduced. There are many different types of randomly accessible memory that we have today. One type of randomly accessible memory is DRAM (dynamic randomly accessible memory) dynamic randomly accessible memory works with transistors there is one transistor for every bit of data a zero or a one. It represents the zeros and ones by turning on or staying off. Because dynamic randomly accessible memory uses transistors to represent ones and zeros it has to have a continues power supplied to the transistors to maintain the one or zero. When power is removed form the dynamic randomly accessible memory it is cleared. DRAM is a SIMM (single in-line memory module) type ram. The benefit of dynamic randomly accessible memory is low cost with high density.
SRAM (Static randomly accessible memory) stores data using four transistors for every bit of data. The transistors in Static randomly accessible memory act as switches when the switches are on they act as a whole circuit and represent a one. When the switch is down the circuit is open and represents a zero. Because of the way Static randomly accessible memory stores data it dos not need a continues supply of power. SRAM is a SIMM (single in-line memory module) type ram.
SDRAM (synchronous dynamic randomly accessible memory) works by synchronizing with the systems bus clock so it is able to receive data in a continues flow making it much faster then SRAM.
Synchronous dynamic randomly accessible memory can take on command and one data packet per hertz or clock cycle. Synchronous dynamic randomly accessible memory is capable of reading or writing 64-bits at a time like the system bus. This data set sent together is called a word. When a word is sent to the synchronous dynamic randomly accessible memory it is stored across eight-DRAM chips that are on to the memory chip. Each DRAM chip receives eight bits of data to make up the 64-bits sent over. This ram is capable of running between 33-166 MHz (mega hertz) and operates on 3.3v (volts). SDRAM is a DIMM (dual in-line memory module) type of ram.
DDR (double-data rate synchronous dynamic randomly accessible memory) is an improved version of SDRAM it is able to receive two consecutive 64-bit data packets or words per clock cycle of the bus in a single command. It doubles the productivity of SDRAM by receiving double the amount of data with in the same amount of time. It is capable of operating at 100-200MHz and runs off of 2.5v. DDR is a DIMM (dual in-line memory module) type of ram.
DDR2 (double-data rate synchronous dynamic randomly accessible memory revision 2) is the second revision of SDRAM it doubles the rate of data transfer of DDR. It is capable of receive four consecutive 64-bit data packets or words per clock cycle of the bus in a single command. Thus doubling the efficiency of DDR. DDR2 also has a buffer to help receive the data faster. DDR2 is capable of operating at 200-533MHz and runs off of 1.8v. DDR2 is a DIMM (dual in-line memory module) type of ram.
DDR3 (double-data rate synchronous dynamic randomly accessible memory revision 3) is the third revision of SDRAM. It doubles the rate of data transfer of DDR2. It is capable of receive eight consecutive 64-bit data packets or words per clock cycle of the bus in a single command. DDR3 is capable of operating at 400-1000MHz and runs off of 1.5. DDR3 is a DIMM (dual in-line memory module) type of ram.
RDRAM (rambus dynamic randomly accessible memory) was mad as another option to DDR. Rambus dynamic randomly accessible memory can transfer data at 16-bit or 32-bit words and can transfer two of either the 16-bit or 32-bit per clock cycle. Rambus dynamic randomly accessible memory can has a memory controller on each one of the chips on the memory chip so it dos not need to use the CPU (central processing unit) or a chipset on the motherboard. Rambus dynamic randomly accessible memory is capable of operating at 400-800MHz and runs off of 2.4. This ram has some cooling issues so it always has a heat sync to help dissipate the heat. RDRAM is a RIMM (Rambus in-line memory module) type of ram.
So in conclusion Memory is a very important part of a computer with out it simple tasks would be very time consuming or not possible. Memory has come a long way from mercury filled vales to memory sticks with IC-Chipsets. With out this simple technology many things would not be possible.