Many laptop computers use different pointing devices, such as a trackball or touch screen to function as a mouse. The MICR reader scans the code on the bottom of cheques to facilitate the sorting of cheques for clearance. These include bar code readers, scanners and the like. The video display or monitor is an essential part of the modern personal computer. Most video cards do not output in radio frequency, and thus you cannot plug your TV into the back of your computer.
Printers are another common output device.
The operating system defines the interface between the user and the hardware. Each authorised user is given a User Id and password. The operating system can restrict access to certain operations, and certain types of data according to the identity of the user. For example, only the accountant, sales manager and general manager may have access to the monthly detailed Sales Report. Alternately, general staff may be forbidden to reverse transactions once they are entered.