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Dynamic RAM  Dynamic RAM This is the most common type of memory used in personal computers, workstations, and servers today. A DRAM chip contains millions of tiny memory cells. Each cell is made up of a transistor and a capacitor, and can contain 1 bit of information-0 or 1. To store a bit of information in a DRAM chip, a tiny amount of power is put into the cell to charge the capacitor. Hence, while reading a bit, the transistor checks for a charge in the capacitor. If a charge is present, then the reading is 1; if not, the reading is 0. However, the problem with DRAM is that the capacitor leaks energy very quickly and can hold the charge for only a fraction of a second. Therefore, a refresh process is required to maintain the charge in the capacitor so that it can retain the information. This refreshing process is carried out multiple times in a second and requires that all cells be accessed, even if the information is not needed. However, the advantage of DRAM over SRAM is that ...

Static RAM Static RAM This is a type of RAM that holds data without an external refresh as long as it is powered. This is in striking contrast with the DRAM which must be refreshed multiple times in a second to hold its data contents. SRAM is made of D flip-flops in which the memory cells flip-flop between 0 and 1 without the use of capacitors. Therefore, there is no need for an external refresh process to be carried out. The limitation of SRAM is that it occupies more space and is more expensive than DRAM. While each transistor on a DRAM chip can store one bit of information, the SRAM chip, on the other hand, requires four to six transistors to store a bit. This means that a DRAM chip can hold at least four times as much data as an SRAM chip of the same size, thereby making SRAM much more expensive. However, SRAM is faster, more reliable than DRAM, and is often used as cache memory. SRAM chips are also used in cars, household appliances, and handheld electronic devices.

Random Access Memory (RAM) RAM is a volatile (stores data only when the power is On) storage area within the computer typically used to store data temporarily so that it can be accessed by the CPU. The information stored in RAM is loaded from the computer's hard disk, and includes data related to the operating system and applications that are currently being executed by the processor. RAM is considered as random access because any memory cell can be directly accessed if its address is known. When the RAM gets full, the computer system operates at a slow speed. When multiple applications are being executed simultaneously and the RAM gets fully occupied by the application's data, it is searched to identify memory portions that have not been utilized. The contents of those locations are then copied onto the hard drive. This action frees up RAM space and enables the system to load other pieces of required data. These days, the applications' and operating system's demand for...

Primary memory Primary memory (or main memory or internal memory) can be directly accessed by the CPU. The CPU continuously reads instructions stored in the primary memory and executes them. Any data that has to be operated by the CPU is also stored there. There are two types of primary memory: RAM and ROM, which are discussed as follows.

Cache Memory Cache memory is an intermediate form of storage between registers and the primary memory. It is used to store instructions and data that are repeatedly required to execute programs thereby improving the overall system speed and increase the performance of the computer. Keeping frequently accessed data and instructions in the cache avoids accessing the slower primary memory. Working of the Cache Memory When a program is being executed and the CPU wants to read data or instructions, then the following steps will be performed: CPU first checks whether the data or instruction is available in cache memory. If it is not present, the CPU reads the data or instructions from the main memory into the processor registers. The CPU also copies it into the cache memory. When the same piece of data/instruction is needed, the CPU reads it from the cache memory instead of the main memory

CPU Registers CPU registers are located inside the processor and are therefore directly accessed by the CPU. Registers are the fastest of all forms of computer data storage.

Memory Hierarchy In contemporary usage, memory usually refers to random access memory, typically DRAM (Dynamic RAM) but memory can also refer to other forms of data storage. In computer terminology, the term storage refers to storage devices that are not directly accessible by the CPU (secondary or tertiary storage). Examples of secondary storage include hard disk drives, optical disc drives, and other devices that are slower than RAM but are used to store data permanently. These days, computers use different types of memory which can be organized in a hierarchy around the CPU, as a trade-off between performance and cost. The memory at a higher level in the storage hierarchy has less capacity to store data, is more expensive, and is fastest to access .