ABSTRACT
The function of a semiconductor memory device in a system is to provide an addressable array of contiguous memory elements, with each element containing a number of basic memory cells, which can be interfaced to the microprocessor system bus. A single digital binary memory cell is a device or circuit which is capable of maintaining the state of its last enabled input value. This state is maintained until the input to the memory is again enabled, and the state of the memory changes to match that of the input signal. Microprocessor system may only read data from read only memory (ROM); ROM devices therefore provide a form of non-volatile memory. Microprocessor peripheral circuits add specific functions such as timers and interrupt controllers to the microprocessor system. Serial input and output devices are used as a means of transferring data between microprocessor systems, or between components within a system, over single data line connections.
