Early computers( 1939-1952)
- First patent on digital computer was by Eckert and mauchly ( ENIAC)
- First digital computer was FERUAT in Canada
- Mainframes: the first commercial digital computers were large, room-sized devices.
- Included the central processing unit (CPU) and some short-term memory into a single silicon “ chip”
using integrated circuits( ICs).
Networking personal computers ( 1985-present)
- Local area networks( LANs) provided the ability to connect many personal computers together.
- Price and performance advances: IT is continuously improving. ( Moore’s law: 18 months the price of a
given integrated circuit(IC) will be half its current price
- All the main components of a modern computer ( Processor, memory, hard drive or storage) have been
getting smaller and costing less.
- Value of IT can be measured not only in the power of the processor but also in the power of the network
that can be accessed through the machine.
Hardware: consists of electronic components and gadgets that input, process, output and store data according
to instructions encoded in computer programs or software.
Input hardware devices: microphones, keyboard, mouse, document scanners
Processing devices: Central processing unit(CPU): selects instructions, processes them, stores results of
operations in memory. Vary in speed, function and cost.
CPU works in conjunction with the computer’s main memory
Special function cards: enhances the computer. Ex. video card.
Output hardware: video displays, printers
Storage hardware: saves data and programs. Ex. magnetic disks
- Binary digits/bits: how computers represent data. ( either zero or one). This can represented through a
switch, magnetism or reflection.
- Sizing computer data: bits are grouped into 8 bit chunks( bytes). Can be character or non character
Kilobytes(K): 1024 bytes Megabytes( MB) : 1024K
1K: 1000 bytes
How does a computer work?
- CPU( central processing unit) transfers the program from disk to main memory.
- To execute an instruction, moves from main memory into the CPU via the data channel or bus
- Cpu contains cache: very fast memory
- Main memory contains operating system(OS) that controls the computer’s resources as well as a block
- Memory swapping: when there is not enough memoy, OS will direct the CPU to swap a black of
memory for new ones. If there is too much memory swapping, the computer will run slowly.
Cache and main memory are volatile: contents are lost when power is off.
Magnetic disks and optical disks are non-volatile.
CPU speed is expressed in cycles called hertz.
What kind of speed and computer an employee needs depends on their job.
Client computers: used of word processing, spreadsheets, database access. Usually have softwares that
allows them to connect to a network.
Servers: provides services to run blog, publish websites, sell goods..etc ( this is faster, larger and more
powerful than client)
Server farm: large collection of computers that coordinate all activities (server farm).
Cloud computing: customers do not have to own the computer they use and hardware are provided as a
service through the web browser. it adds the ability to store and success data remotely and to pay for it as a
service. ex. internet
- More efficient because customers can also pay for what they use and don’t have to own it to use it.
- Grid computing: several computers are used to address a single problem at the same time. Uses
software to divide and apportion pieces of a program among several computers.
Computer software can be categorized into two varieties:
1) Operating systems: large systems that control the computer’s resources. ex. windows
2) Application software: programs that perform specific user tasks. Ex. word, excel Constraints of softwares:
- Each version of an operating system is written for particular type of hardware. Ex. windows works only
on processors that conform to the intel instruction set( commands that a CPU can process)
- Application programs are written to use a particular operating system. Ex. windows and mac versions of
Four major operating systems:
- Windows: business users.
- Mac os: primary for graphic artists
- Unix: not used for average business users and more for scientific and engineering communities
- Linux: version of unix developed by the open source community( loosely coupled group of
programmers who mostly volunteer their time to contribute code to develop and maintain linux. Can run
on both client and servers. IBM is the proponent of linux.
License: buying the right to use the program. Linux has no license fee between its owned by open source
Application software: consists of programs that perform a business function. Ex. QuickBooks, excel.
Categories of application programs:
- Horizontal-market application: provides capabilities common across all organizations and industries.
Ex. word and PowerPoint ( stuff purchased off the shelf)
- Vertical-market application: serves the needs of specific industry. Ex. dental office programs to
schedule and bill patients. This application can be altered and customized.
- One of a kind application: developed for a specific unique need. Ex. CRA
Some application software does not neatly fit into horizontal or vertical category. Ex. CRM (customer
relationship management) can be purchased off the shelf but can also be customized.
Custom developed software is also called tailor-made software. This is difficult and risky (time consuming and
expensive). There is also an adaption cost to developed tailored software in response to changing needs and
technologies. This option is used as a last resort.
Browsers: have characteristics of both an application and operating software.
Firmware: computer software installed into devices like printers, print servers and various types of
communication devices. Becomes part of the device’s memory.
Basic input/output system (BIOS): important piece of firmware that is used when a computer is initially started
up. in order to start the computer again, it has to load BIOS from ROM ( non-volatile read only memory) and
run through the commands provided by the firmware. BIOS checks to make sure that the memory and input
devices are functional and then operating system will load.
Thin client: browser that requires only a browser . do not require the installation and administration of client
software Thick client: application that requires program other than a browser on the user’s computer. ( Microsoft
outlook). Does not need the access to the network to run.
Think and thin refers to the amount of code that must run on the client computer. Client and server computers
can run different operating systems.