Relationship Between Hardware and Software

Relationship between Hardware and Software • Hardware and software are mutually dependent on each other. Both of them must work together to make a computer produce a useful output. • Software cannot be utilized without supporting hardware. • Hardware without set of programs to operate upon cannot be utilized and is useless. • To get a particular job done on the computer, relevant software should be loaded into the hardware • Hardware is a one-time expense. • Software development is very expensive and is a continuing expense. • Different software applications can be loaded on a hardware to run different jobs. • A software acts as an interface between the user and the hardware. • If hardware is the 'heart' of a computer system, then software is its 'soul'. Both are complimentary to each other. Computer Memory • Memory is used to store the information (programs and data) that the computer is currently using. It is sometimes called main or primary memory. • RAM - random access memory. This means that any location in memory may be accessed in the same amount of time as any other location. Memory access means one of two things, either the CPU is reading from a memory location or the CPU is writing to a memory location. When the CPU reads from a memory location, the contents of the memory location are copied to a CPU register. When the CPU writes to a memory location, the CPU copies the contents of a CPU register to the memory location, overwriting the previous contents of the location. The CPU cannot carry out any other operations on memory locations. • RAM is a form of short term or volatile memory. Information stored in short term storage is lost when the computer is switched off (or when power fails e.g. if you pull out the power lead!). There is therefore a requirement for permanent or long term storage which is also referred to as secondary storage or auxiliary storage. This role is fulfilled by disk and tape storage. 1.3.1 Random Access Memory (RAM) RAM(Random Access Memory) is the internal memory of the CPU for storing data, program and program result. It is read/write memory which stores data until the machine is working. As soon as the machine is switched off, data is erased. Access time in RAM is independent of the address that is, each storage location inside the memory is as easy to reach as other locations and takes the same amount of time. Data in the RAM can be accessed randomly but it is very expensive. RAM is volatile, i.e. data stored in it is lost when we switch off the computer or if there is a power failure. Hence a backup uninterruptible power system(UPS) is often used with computers. RAM is small, both in terms of its physical size and in the amount of data it can hold. RAM is of two types • Static RAM (SRAM) • Dynamic RAM (DRAM) 1)Static RAM (SRAM) The word static indicates that the memory retains its contents as long as power is being supplied. However, data is lost when the power gets down due to volatile nature. SRAM chips use a matrix of 6-transistors and no capacitors. Transistors do not require power to prevent leakage, so SRAM need not have to be refreshed on a regular basis. Because of the extra space in the matrix, SRAM uses more chips than DRAM for the same amount of storage space, thus making the manufacturing costs higher. So SRAM is used as cache memory and has very fast access. Characteristic of the Static RAM • • • • • • • It has long life There is no need to refresh Faster Used as cache memory Large size Expensive High power consumption 2)Dynamic RAM (DRAM) DRAM, unlike SRAM, must be continually refreshed in order to maintain the data. This is done by placing the memory on a refresh circuit that rewrites the data several hundred times per second. DRAM is used for most system memory because it is cheap and small. All DRAMs are made up of memory cells which are composed of one capacitor and one transistor. Characteristics of the Dynamic RAM • • • • • • • It has short data lifetime Need to be refreshed continuously Slower as compared to SRAM Used as RAM Lesser in size Less expensive Less power consumption