Page 26 - UNI 101 Computer Science Handout.

Faculty of Nursing
Adult care Nursing Department

known of these is IBM’s channel architecture, a technology that has been continually updated to achieve

ever-increasing I/O capability. Many modern computer systems satisfy the demand for computing

power by integrating multiple processors. Multiprocessing and clustering are often used together to
provide the tremendous computing power offered in many large scale modern systems, including

supercomputer systems.

In fact, modern large-scale computers are predominantly designed as carefully integrated combinations

of multiprocessing and clustering technology. The primary method used for this purpose utilizes spare
CPU capability available when individual computers on a large network facility, such as the Internet, are

working at less than full capacity. This technique, gradually increasing in importance, is known variously

as grid computing or cloud computing. Interestingly, despite the previous discussion, it is sometimes not
practical to utilize the available CPU capability of a system effectively. A programmer may wish to test a

program, for example, that presents a security or failure risk to the production work of the system. Or

there may be a need for systems to support a number of tasks in a facility where it may be more cost

effective to provide and support a single large system rather than a number of smaller systems.

One important solution to situations such as these is a technique called virtualization, in which an

individual computer system is used to simulate multiple computers, all sharing the same CPU and I/O

facilities. The simulated machines are known as virtual computers. Each virtual computer runs its own

operating system and programs. Special hardware and software is designed to assure isolation between

the various virtual computers, to prevent unwanted interactions, such as security breaches. Many
organizations consider virtualization an important tool in building large, cost effective, system solutions.

The main memory, often known as primary storage, working storage, or RAM (for random access

memory), holds programs and data for access by the CPU. Primary storage is made up of a large number

of cells, each numbered and individually addressable. Each cell holds a single binary number
representing part of a data value or part of an instruction. The smallest addressable size of the cell in

most current computers is 8 bits, known as a byte of memory. Eight bits of memory can only hold 256

different patterns, so neigh boring cells in memory are nearly always combined to form groupings with
26 Academic Year 2025/2026