Background

Personal workstations. Interest in window management systems has expanded with the proliferation of personal computers. Personal workstations are personal computers that are used by only one person at a time but provide far more power than typical home computers. A personal workstation will usually have a processor that can execute over one million instructions per second, a hard disk that can hold over 20 million bytes of data, a memory of at least one million bytes, some number of input/output options, such as RS-232, Ethernet, IEEE 488, floppies, etc., and a high-performance screen that is capable of graphics. Most personal workstations currently use high-resolution bit-map screens (about 800 x 1000) where each point on the screen (called a pixel) is associated with one bit of memory. Each pixel can be either on or off (white or black). Many personal workstations have some sort of hardware that allows screen operations to run swiftly, and some offer color screens as an option. Most personal workstations run an operating system, such as Unix, 5 that allows the user to run a number of different jobs (sometimes called processes) at the same time. For example, the user might specify that a compilation should continue to run (in the background) while the user enters the editor to work on a different file. Even with the high performance of a personal workstation, there will unfortunately always be jobs that cannot be processed instantly (ie, fast enough so the user does not notice the delay). With multiprocessing the user does not have to wait idly for jobs to be finished, so time can be used more effectively.