The computer software is divisible into several modules in terms of function. Figure shows the relationships of these modules. The monitor is a small program permanently stored in read-only memory (ROM) in the microcomputer. It performs basic traffic direction and boots up the supervisor. That is, when the computer is switched on, the monitor expects to find a program waiting to be read from a mass storage device. It initiates reading of this program, which is, in fact, the remainder of the permanent software. . | ROBOTS AND SMART MACHINES COMPUTER HARDWARE AND SOFTWARE ORGANIZATION Software Organization Basic Operation. The computer software is divisible into several modules in terms of function. Figure shows the relationships of these modules. The monitor is a small program permanently stored in read-only memory ROM in the microcomputer. It performs basic traffic direction and boots up the supervisor. That is when the computer is switched on the monitor expects to find a program waiting to be read from a mass storage device. It initiates reading of this program which is in fact the remainder of the permanent software. Thus the software system pulls itself up by its own bootstraps. This procedure is necessitated by the volatile nature of the devices used for random access memory RAM . Random access memory is the primary memory of the computer. Information stored in RAM or ROM can be directly addressed by the computer and so it can be accessed in minimal time. RAM is called volatile because the information stored in it is lost if the power is turned off. ROM is nonvolatile. That is why the monitor at least must be stored in ROM. FIGURE Computer software architecture typical of industrial robots. In an industrial robot storage of the entire permanent system program in ROM is a viable option. ROM is more expensive than RAM but this configuration eliminates the bootstrap operation. There is a much more important objection to storage of the system program in ROM than cost the lack of flexibility in terms of updating the system program. It has become customary for robot manufacturers to peri STANDARD HANDBOOK OF MACHINE DESIGN odically issue updated versions of the system program which provide additional capabilities. If the system program is stored on a tape cassette or disk updating requires only substitution of the new cassette or disk for the old. If the system program is on ROM installation of an update may be much more complicated. .
