TOPIC 2 - Part 2 Flashcards
Operating system (OS)
An operating system (OS) is a set of software that controls the computer’s hardware
resources and provides services for computer programs. It acts as an intermediary between software applications (i.e.
programs) and the computer hardware.
What services does operating system provide?
Peripheral communication
Memory management
Resource monitoring and multitasking
Networking
Disk access and data management
Security
What are the main software applications?
Word processors
Spreadsheets
Database management systems
Web browsers
Email
Computer Aided Design (CAD)
Graphic processing software
Decimal number system
The decimal number system is a positional system that uses ten digits (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9) to represent any number, no matter how large or small. The decimal number system (or base-10) has ten as its base and it is the most widely-used number system.
Binary number system
The binary number system is a positional system that uses two digits (0 and 1) to represent any number. The binary number system (or base—2) has two as its base.
Binary number system and negative numbers
Two’s complement is the way most modern computers represent signed binary numbers. The main advantage of this representation is that addition, subtraction and multiplication are carried out easily. Suppose that an 8 bit register stores the number 28. In this representation, positive binary numbers start with 0 while negative binary numbers start with 1.
Hexadecimal number system
The hexadecimal number system is a positional system that uses 16 digits (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E and F) to represent any number. Digits A to F represent quantities from 10 to 15, thus A = 10, B = 11, C = 12, D = 13, E = 14 and F = 15. The hexadecimal number system (or base-16) has sixteen as its base and is used in computer science. Numbers represented in this system are known as hexadecimal numbers.
The AND Boolean operator
When both switches are open (0) the light is off (0)
When switch number 1 is open (0) and switch number 2 closed (1) the light is off (0)
When switch number 1 is closed (1) and switch number 2 open (0) the light is off (0)
When both switches are closed (1) the light is on (1)
The OR Boolean operator
When both switches are open (0) the light is off (0)
When switch number 1 is open (0) and switch number 2 closed (1) the light is on (1)
When switch number 1 is closed (1) and switch number 2 open (0) the light is on (1)
When both switches are closed (1) the light is on (1)
The NOT Boolean operator
This Boolean operator has a single input and a single output. What this operator
accomplishes is to take the input and output the reverse. If the input is 1/true the output will be O/false, and if the input is O/false the output will be 1/true.
The NAND Boolean operator
The NAND Boolean operator is similar to the AND Boolean operator, but with its outputs
inverted. As in the AND Boolean operator, the NAND Boolean operator has four states that it can be in, Instead of having an output of 1/true when both the inputs are 1/true, as is the case for the AND Boolean operator, the NAND Boolean operator has an output of 1/true when one or both inputs are O/false.
The NOR Boolean operator
The NOR Boolean operator is similar to the OR Boolean operator but with its outputs
inverted. As in the OR Boolean operator the NOR Boolean operator has four states that it can be in, Instead of having an output of 1/true when one or both inputs are l/true, as is the case for the OR Boolean operator, the NOR Boolean operator has an output of 1/true when both inputs are 0/false.
The XOR (exclusive OR) Boolean operator
The XOR Boolean operator can be thought of as one or the other but not both. As in the OR Boolean operator, the XOR Boolean operator has four states that it can be in.
