Chapter 4: Hardware and Software

Hardware consists of electronic components and related gadgetry that input,process,output,and store data according to instructions encoded in computer programs and software.
Input devices are the keyboard,mouse, document scanners,and bar code scanners.
Processing devices include the central processing unit (CPU) which is sometimes called "the brain" of the computer.
The CPU selects,instructions, processes them,performs arithmetic and logical comparisons, and stores results of operations in memory.
Dual processor is a computer with two CPU's . A Quad-processor is a computer that has four CPU's.
The CPU reads data and instructions from memory, and it stores results of computation in main memory. Main memory is sometimes called RAM( random access memory).
Special function cards can be added to the computer to augment its basic capabilities.
Output hardware- consists of video displays,printers, audio speakers,overhead projectors,and other special-purpose devices,such as large flatbed plotters.
Storage hardware- saves data and programs. ex: magnetic disks,CDs, DVDs,etc.
Computers represent data using binary digits,called bits. A bit is either a zero or a one. Bits are used for computer data because they are easy to represent electronically.
Storage Capacity terminology
Byte- number of bits to represent one character
Kilobytes----1,024 bytes-----K(abbreviation)
Megabyte----1,024K=1,048,576 bytes----MB
Gigabyte -----1,024 MB=1,073,741,824 bytes---GB
Terabyte-----1,024 GB=1,099,511,627,776 bytes

To run a program or process data,the computer first transfers the program or data from disk to the main memory. Then,to execute an instruction,it moves the instruction from main memory into the CPU via the data channel or bus. The CPU has a small amount of very fast memory called cache.
Operating system(OS) is a program that controls the computer's resources.
Memory swapping is the movement of programs and data into and out of memory. If a computer has insufficient memory for its workload, such swapping will degrade system performance.
CPUs today are classified as 32-bit or 64-bit. The cache and main memory are volatile,meaning that their contents are lost when power is off. Magnetic and optical disks are nonvolatile,meaning that their contents survive when power is off.
Users employ client computers for word processing,spreadsheets,database access,and so forth.Servers provide some service. Some servers process email;other process websites;others process;large,shared databases;and some provide all of these functions or other,similar functions. A collections of servers is called a server farm.
A grid is a network of computers that operates as an integrated whole;the grid appears to be a single computer.
Cloud refers to the computing network on the internet. Instruction set is the commands that a CPU can process.
Four Major Operating Systems
Windows-an operating system designed and sold by Microsoft. it is the most widely used operating system.
Mac OS- an operating system developed by Apple. It was developed for the Powerpc, but as of 2006 will run on Intel processors as well.
Unix- an operating system that was developed at bells labs in the 1970s. It has bee the workhorse of the scientific and engineering communities since then.
Linux-a version of unix that was developed by the open source community.It is a popular operating system for web servers.
When you buy a computer program,you are not actually buying that program. Instead, you are buying a license to use that program. large organizaitons buy a site license, which is a flat fee that authorizes the company to install the product on all of the company's computers.
Application software performs a service or function. ex: Microsoft Excel,Word, Quickbooks,etc.
Horizontal-market application is a software that provides capabilities common across all organizations and industries.
Vertical-market application software serves the needs of a specific industry.
One-of-a-kind application is a software that is developed for a specific,unique need.
You can buy computer software off-the-shelf software,off-the-shelf with alternation software,or tailor made,which is called custom developed software.
Firmware is a computer that is installed into devices such as printers,print servers, and various types of communication devices.
Client-server applications require code on both the client and the server. Email is a good example.
Thin Client- a client-server application that requires nothing more than a browser.
Thick Client- requires programs other than a browser on the user's computer.

Open source means that the source code of the program is available to the public. Source codes is computer code as written by humans and that is understandable by humans. Source code is compiled into a machine code that is processed by a computer. Machine code in general not understandable by humans and cannot be modified. In a closed source (ex. Microsoft Office) the source is highly protected and only available to trusted employees and carefully vetted contractors.
Because of Moore's law, hardware,and software will likely undergo major changes by 2020.