The most common input device used with microcomputers is the keyboard. Output can be directed to a video monitor, printer, or disk drive. Composite monitors are capable of displaying text and low resolution graphics. TTL and RGB monitors can display high resolution graphics. Dot matrix printers produce hardcopy at high speed with varying degrees of resolution, whereas fully formed character printers produce letter quality copy.
RAM memory is the workspace used by the CPU for storing data and programs.
It is volatile. ROM memory holds instructions supplied by the manufacturer. ROM is nonvolatile. Memory is allocated in eight bit quantities called bytes. One character occupies one byte of memory.