INFS214, INTRODUCTION TO COMPUTING

LECTURE 1...( COMPONENTS OF A COMPUTER SYSTEM AND MODES OF USE)
•Hardware is the physical components that make up the computer system.

•Software is the set of instructions (programs) that make the computer hardware usable. 

•An input device is a physical component that transmits data to the computer. 

•A storage device is a physical component that stores data for use by the computer. 

•An output device is a physical component displays data transmitted from the computer. 

•Operating system software comprises the programs that make the computer hardware available for use, often unseen by the user. 

•Generic/general purpose applications software comprises programs that can be used for many tasks, such as a word 

•Processor, spreadsheet software and database software.

LECTURE 2...( FUNCTIONS OF OPERATING SYSTEMS)

•The main aims and features of an operating system are to manage the resources of
the computer system:

– processor management – decide on appropriate scheduling algorithms – file management – input/output management – memory management


•Scheduling tries to ensure that the processor is working to its full potential:
−that the processor is not idle, waiting for I/O
−that I/O-bound processes do not wait for the processor when they only need to use it a little
−that processor-bound processes do not block other processes.

•Linker and loader software load and keep track of processes and their data.

 
•Virtual memory is a small amount of fast access storage between the disk and the memory. 

•Peripherals and processes that want to use the processor send an interrupt:
−a program interrupt signals an error in a program.
−an I/O interrupt signals that a data transfer is complete or an error has occurred.
−a timer interrupt signals that a time-critical activity needs attention.
−a hardware error signals that some device has failed.

LECTURE 3... ( COMPUTER ARCHITECTURE AND THE FETCH-EXECUTE CYCLE)

•The basic von Neumann architecture has a single processor which uses a fetch–decode–execute cycle for the sequence of instructions which make up a program. 

•The Von Neumann Architecture contains special registers that allow fast access to data and are used to execute a program: 

−program counter (PC) 

−current instruction register (CIR) 

−memory address register (MAR) 

−memory data register (MDR) 

•In the fetch stage: 

−The address in the PC is copied to the MAR and the PC is incremented.
−The instruction in the MAR address is loaded into the MDR and then the CIR. 

•In the execute stage:
−If the instruction is a jump instruction then its operand is loaded into the PC and a

new fetch stage starts.
−If the instruction is not a jump instruction, it is executed. A new fetch stage starts.

LECTURE 4... ( DATA REPRESENTATION)

Computers do not recorgnise text, sound and images the same way we do. Computers use binary digits which are 0s and 1s. Therefore the computer needs to represent data in a format
that it understands

•Text is encoded as a number that is then represented by a binary number.
•For this character set eight bits are used to store a single character. Using a byte (eight bits) for a character, we have 256 codes (i.e. 256 different eight-bit binary values). This is enough to represent each of the characters on a standard keyboard

•Images are encoded into computers as bitmaps or vectors.
•Bitmap images are made out of small parts called pixels. Vector images are made using coordinates and geometry.
•Graphics on a screen are made up of tiny blocks called pixels. The more pixels on the screen, the higher the resolution and the better the quality of the picture will be. The higher the image resolution, the more memory is needed to store the graphic.

The sound quality is affected by the following:
–Sample rate
–Bit rate Bit depth

LECTURE 5...(DATABASES)

•A flat file consists of a large number of records each of which comprises a number of fields.

•Each field has its own data type and holds a single item of data. 

•Flat-fi le systems tend to lead to:
−separation and isolation of data
−duplication of data
−data dependence
−data inconsistencies
−difficulty in changing applications programs. 

•A DBMS is a piece of software that provides the following facilities:
−a data defi nition language (DDL) that the database designer uses to defi ne the tables of the database
−a data dictionary that contains all design information
−a data manipulation language (DML) for inserting, amending and deleting data records

LECTURE 6...( SIMULATION AND REAL-TIME PROCESSING)

When you describe a real-time application, you must mention:
−the “world” of the application
−the hardware necessary to allow the input and output needed to operate the system
−the decisions that the software must take.
•A sensor records information from its environment:
−Light and temperature sensors convert the reading into a variable voltage reading. It must be converted by an

analogue-to-digital converter.


−A pressure pad gives a digital signal – pressed or not pressed.


The processor makes a decision based on sensor input and then activates an actuator to take action.

Simulation can be used to model a situation:



−to produce results faster than carrying out the process (e.g. growing a generation of flowers)
−to produce results that would be dangerous to obtain in real life (e.g. in a nuclear reactor)


−to produce result more cost effectively than building a prototype.


Simulation can test the feasibility of a design without the building or vehicle having to be built at great cost.

REFERENCES:

lecture Notes: Dr. Philip Nukpe & Mr. Michael Allotey, College of Education, School of Information and Communication Studies, Department of Information Studies, 2018/2019 ACADEMIC YEAR.