Computer processing

1.1 Computer processing

All computer systems, whether it’s a desktop, laptop, tablet, smart phone, gaming console, or a special-purpose device like a car’s navigation system, share certain characteristics. The details vary, but they all process data in similar ways. W hile the majority of this book deals with the development of software, w e’ll begin with an overview of computer processing to set the context. It’s important to establish some fundamental terminology and see how key pieces of a computer system interact.

A computer system is made up of hardware and software. The hardware components of a computer system are the physical, tangible pieces that support the computing effort. They include chips, boxes, wires, keyboards, speakers, disks, memory cards, USB flash drives (also called jump drives), cables, plugs, printers, mice, monitors, routers, and so on. If you can physically touch it and it can be

considered part of a computer system, then it is computer hardware.

The hardware components of a computer are essentially useless without instructions to tell them what to do. A program is a series of instructions that the hardware executes one after another. Software

consists of programs and the data those programs use. Software is the intangible counterpart to the physical hardware components.

Together they form a tool that we can use to help solve problems.

The key hardware components in a computer system are

■ central processing unit (CPU)

■ input/output (I/O) devices

■ main memory

■ secondary memory devices

Each of these hardware components is described in detail in the next section. For now, let’s simply examine their basic roles. The central processing unit (CPU) is the device that executes the individual commands of a program. Input/output (I/O) devices , such as the keyboard, mouse, and monitor, allow a human being to interact with the computer.

Programs and data are held in storage devices called memory, which fall into two categories: main memory and secondary memory. Main memory is the storage device that holds the software while it is being processed by the CPU. Secondary memory devices store software in a relatively permanent manner. The most important secondary memory device of a typical computer system is the hard disk that resides inside the main computer box. A USB flash drive is also an important secondary

memory device. A typical USB flash drive cannot store nearly as much information as a hard disk. USB flash drives have the advantage of portability; they can be removed temporarily or moved from computer to computer as needed. Another portable secondary memory device is the compact disc (CD).