Ch. 1: Structure and Organization of Information Systems Flashcards
What is a bit?
This is the smallest possible unit of information. One bit corresponds to the amount of information in an answer to a question with only two possibilities.
Please give an example of the physical or electrotechnical replication of 1 and 0.
Possible examples are – among others:
- Lamp: Off/On
- Switch position: Off/On
- Change of elevation and depression on CD, DVD, or Blu-Ray-Disc
- Magnetic state of magnetizable material
Please name and explain the Boolean operations.
- The Boolean operation “AND” is a two-digit operation. It evaluates two Boolean values X and Y to 1 if both values are 1. Otherwise, AND evaluates to 0.
- The Boolean operation “OR” is also a two-digit operation. It evaluates two values X and Y to be 1 if at least one of the values is 1.
- The operation “NOT” has one digit. It simply negates the value X. The value 1 is evaluated as 0, the value 0 as 1.
What does the Boolean operator OR evaluate to?
To two values, x and y, to 1, if any value is 1.
Please describe how individual digits and letters can be represented as a sequence of 0 and 1.
There are defined mappings and standards for this, for example, ASCII or UTF-8. In UTF-8, the sequence 01010011 represents the letter “S.” In order to save in binary letters and digits, you only have to look up the UTF-8 table.
What was the novel idea of von Neumann architecture at the time it was invented?
Von Neumann developed the idea of storing the computer programs together with the data to be processed in a shared memory (the main memory) of the computer. Since the programs are also in a changeable memory, the rules and instructions on how the data are processed can also be adapted without having to exchange the hardware components of the computer system. Von Neumann thus constructed a computing system that, unlike what was common for computing systems at the time, was not intended to solve a specific problem.
Please name the units of the von Neumann architecture.
- Memory
- Control unit (as part of the CPU)
- Arithmetic logical unit (as part of the CPU)
- Input/output units
- Bus system
What does the acronym ALU stand for?
Arithmetical logical unit.
Please differentiate the tasks of the control unit and the arithmetic unit.
The control unit is the coordinator in the CPU. First of all, it is responsible for loading the commands to be executed in a program from the memory into the CPU in the correct order and for interpreting them. In addition, the source and target of the data to be processed must be interconnected with the arithmetic logical unit, and the arithmetic logical unit must be informed which calculation it should carry out with the data.
The arithmetic logical unit is the only component of the computer in which calculations are carried out. The arithmetic logical unit has a number of executable arithmetic and logical functions. All binary operations of computer systems are carried out in that unit.
What do the memory, input/output units and bus system do?
- The memory of a von Neumann computer is used to store binary coded data and programs; there is only one type of memory. The available memory is divided into small areas that are numbered consecutively with a unique address. Data that are stored in a memory cell can be called up via their address. When accessing memory, the memory area in the storage medium is located and then read out or changed.
- The I/O units are the interface between the system and its surrounding environment. They are responsible for the flow of incoming and outgoing data and programs.
- The bus is a data transmission system used by all units for communication. In a von Neumann computer, all data are transferred over the bus.
What is a distributed system?
This is a software system that can only be used in conjunction with several computers connected via a communication network.
Please name the typical elements and their tasks in distributed systems.
Server: refers to computers that offer functions that can be called up by other computers via a communication network.
Client: computers that use the services offered by servers
Communication network: network for communication between computer systems. It routes messages from one computer to another.
Message: information sent between computers via the communication network.
Please name two practical examples of the interaction between client and server.
- The browser (client) is used to order something from an online shop (server).
- The laptop (client) should print out a document via a network printer (server).
- The mobile phone (client) retrieves the current weather data from a weather service (server).
What is a protocol in conceptual model for communication?
A set of conventions that govern the interaction of processes, devices, and other components within a system is a protocol, such as TCP/IP or OSI.
Please name the seven layers of the OSI reference model.
Application, presentation, session, transport, network, link, and physical layer.