Revision. Paper 1 & Paper 2

Transcription

1 Revision Paper 1 & Paper 2

2 BT-FEST Because Therefore For Example So That (This is the old PEE structure in disguise, with some key connectives to help writing style) As you are writing a sentence, try saying each connective with a slight rising inflection For example One way to improve CPU performance is to increase the cache...because this reduces the number of times the RAM is accessed...therefore the execution time is quicker...because the processor is not waiting for instructions to be fetched from the RAM Now you may not quite write it like this, but checking for because therefore for example and so that... will prompt you to think about adding examples and reasons to your answer. Another way to think of this is answering the questions What How Why What If.. You can use the connective such as... in the same way as for example... Use whatever connectives suit you best: one connective = one extra mark

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8 1. The CPU is split into two major parts. Two of these parts are the Arithmetic Logic Unit (ALU) and the Control Unit. a) Describe the purpose of the ALU b) Describe the purpose of the Control Unit Model answer

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10 Unit 8 Data representation

11 Why use Hex Much simpler to remember a hex value than a binary value Quicker to write or type since a hex digit only takes up 1 character, not 4 Less likely to make an error with fewer characters Easy to convert to and from binary

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13 Unit 7 Logic and Truth Tables

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24 Secondar y M emor y Secondary Memory is where programs and data are kept on a long term basis.common secondary storage devices are hard disk and optical disks.the hard disk has huge storage capacity compared to main memory.the hard disk is usually contained inside the case of the computer. Examples of Secondary memory:flash(usb),cd,dvd,storage TAPE,SMART MEDIA,REMOVABLE HARD DRIVE,mICRO DRIVE,MEMORY STICK,SMART CARD,PC CARD.

25 Oper ating Systems and Types of User Inter face There are 3 types main operating systems to choose from for your computer. Windows, Linux and Mac OS. There are 5 main types of user interface: Command Line-a method of interaction called the command line interface (CLI). This is a text-only service with feedback from the OS appearing in text. Using a CLI requires knowledge of the commands. Graphical User Interface(GUI)- Provides an environment with icons and menus. This type of interface is called the graphical user interface (GUI) because the user interacts with images through a mouse, keyboard or touchscreen

26 CPU There are three main parts of the Von Neumann architecture CPU: the Control Unit (CU), the Arithmetic Logic Unit (ALU) and the registers. The CU manages and monitors hardware so it goes to the right place, it manages the inputs and outputs ensuring these are dealt with correctly and, finally, it manages the FE cycle. The ALU has two parts - the arithmetic part and the logic part. The arithmetic part is where it carries out mathematical calculations. An example could be 2+2=4-1=3. The logic unit deals with logical operations such as True/False.

27 Operating Systems and Types of User Interface There are 3 types main operating systems to choose from for your computer. Windows, Linux and Mac OS. Graphical User Interface(GUI)- Provides an environment with icons and menus. This type of interface is called the graphical user interface (GUI) because the user interacts with images through a mouse, keyboard or touchscreen

28 Virtual Memory Keywords Volatile- Loses all data when the power is gone RAM- Random Access Memory Virtual Memory: Is a section of volatile memory created temporarily on the storage drive. It is created when a computer is running many processes at once and RAM is running low. It is created when the main memory (RAM) is full or nearly full It s the same as RAM but it is much slower Stored in the hard disk

29 RAM & ROM RAM is an abbreviation for Random Access Memory. RAM is also known as main memory. It is used to store programs that are currently being used. RAM must be refreshed every millisecond. RAM is also volatile so if the electricity/ the power goes out, it will lose all the unsaved memory. ROM is an abbreviation for Read Only Memory, it is non volatile so if the power goes out, memory won t be lost. ROM stores the boot up sequence and you can only edit it when it is off, but it is rarely touched. When the computer boots up, the CPU accesses the ROM so it can access it faster and boot it up successfully.

30 Volatile and nonvolatile memor y Memory can either be volatile or non volatile. Volatile memory is a type of memory that when the computer loses power then it loses its data. An example of this is RAM (random access memory). Volatile memory is the exact opposite, for this type of memory the memory is always saved even if the computer loses its power. An example of this is ROM (read only memory) Vola t ile Non v ola t ile

31 REGISTERS Registers are simply small storage devices built into a computer s main processor (CPU - Central Processing Unit), which have different programs built into these registers that do specific tasks, by storing specific data. There are 5 registers in the CPU: - CIR - Current Instruction Register - holds the instruction that is currently being executed. - MAR - Memory Address Register - Hold the memory address from which data will be fetched to the CPU, or the address to which data will be sent stored. - MDR - Memory Data Register - stores the data to be contained in the computer storage, like RAM, or the data after a fetch from RAM. - ACC - Accumulator - Stores calculations and logical operations temporarily until it can stored in RAM after an FDE cycle. - PC - Program Counter - Stores the data during the FDE cycle in progress. When a new instruction is fetched, it increases its stored value by one.

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