2.1.1 Modified.pdf

Computer Organisation IB Computer Science Content developed by Dartford Grammar School Computer Science Department IB Theory of Knowledge Content developed by Dartford Grammar School Computer Science Department Evaluate the use of natural resources! How...

Computer Organisation IB Computer Science Content developed by Dartford Grammar School Computer Science Department IB Theory of Knowledge Content developed by Dartford Grammar School Computer Science Department Evaluate the use of natural resources! How are CPUs made? Content developed by Dartford Grammar School Computer Science Department HL & SL 2 Overview Computer architecture 2.1.1 Outline the architecture of the central processing unit (CPU) and the functions of the arithmetic logic unit (ALU) and the control unit (CU) and the registers within the CPU 2.1.2 Describe primary memory. 2 Distinguish between random access memory (RAM) and read-only memory (ROM), and their use in primary memory 2.1.3 Explain the use of cache memory 2.1.4 Explain the machine instruction cycle Secondary memory 2.1.5 Identify the need for persistent storage Operating systems and application systems 2.1.6 Describe the main functions of an operating system 2.1.7 Outline the use of a range of application software 2.1.8 Identify common features of applications Binary representation 2.1.9 Define the terms: bit, byte, binary, denary/decimal, hexadecimal 2.1.10 Outline the way in which data is represented in the computer Simple logic gates 2.1.11 Define the Boolean operators: AND, OR, NOT, NAND, NOR and XOR 2.1.12 Construct truth tables using the above operators 2.1.13 Construct a logic diagram using AND, OR, NOT, NAND, NOR and XOR gates Content developed by Dartford Grammar School Computer Science Department  Topic 2.1.1 Pg22 Outline the architecture of the Central processing unit (CPU) and the functions of the arithmetic logic unit (ALU) and the control unit (CU) and the registers within the CPU. Content developed by Dartford Grammar School Computer Science Department Learning Objectives Define the terms CPU, ALU, CU, MAR, MDR, Address bus and Data Bus Develop a block diagram of the CPU showing connections between the elements of the CPU, input, output and storage Content developed by Dartford Grammar School Computer Science Department  Key abbreviations CPU = Central Processing Unit ALU = Arithmetic Logic Unit CU = Control Unit MAR = Memory Address Register MDR = Memory Data Register PC = Program Counter Acc = Accumulator Content developed by Dartford Grammar School Computer Science Department Computer system A computer system is a combination of hardware and software components and have an input, process, output and storage. Output Input (Data) Process (Information) Storage Content developed by Dartford Grammar School Computer Science Department CPU (Central Processing Unit) The key component of a computer system, which contains the circuitry necessary to fetch data/instructions from and to main memory (RAM), decode and execute program instructions. Content developed by Dartford Grammar School Computer Science Department Simplified model: CPU, RAM Address Bus ALU MAR Data Bus Data Bus RAM CPU MDR Cache (Primary Memory) Other Control Bus registers CU Content developed by Dartford Grammar School Computer Science Department Simplified model: CPU, I/O devices, Storage CPU RAM (Primary I/O controller Memory) Output Input Storage device device device Content developed by Dartford Grammar School Computer Science Department  Exam note! Students must be able to reproduce a block diagram showing the relationship between the elements of the CPU, input/output and storage. The only registers that need to be indicated are the MDR and MAR. Content developed by Dartford Grammar School Computer Science Department Function of the ALU Part of the CPU that does all the arithmetic (+/-) and logical (AND/OR) or input/output operations/calculations Sometimes an ALU is referred to a ‘core’, hence computers with dual core technology have two ALUs to process two calculations simultaneously using parallel processing. Content developed by Dartford Grammar School Computer Science Department Two functions of the CU The Control Unit (CU) is responsible for the operation of the CPU. It handles the loading/fetching of new commands from primary memory into the CPU and the sequence of their execution – decoding of these instructions. Also, it directs the data flow and the operation of the ALU. Content developed by Dartford Grammar School Computer Science Department Programs/data are loaded from storage, into memory (RAM) and executed one instruction at a time by the CPU Content developed by Dartford Grammar School Computer Science Department CPU needs it’s own ‘memory’ Registers: they are small, very fast circuits that store intermediate values from calculations or instructions inside the CPU. There are many registers, but the most important ones are: – MAR – MDR – Accumulator – Program Counter Content developed by Dartford Grammar School Computer Science Department PC (Program Counter) PC stores the memory(RAM) address of the next instruction/data to be fetched from RAM. PC is connected to the address bus. PC contains a memory/RAM address. Content developed by Dartford Grammar School Computer Science Department MAR (Memory Address Register) MAR stores the memory(RAM) address of the current instruction/data to be fetched from RAM MAR is connected to the address bus. MAR contains a memory address. Content developed by Dartford Grammar School Computer Science Department  MDR (Memory Data Register) MDR is connected to the data bus. MDR holds data that will be written to the RAM or that was read from RAM. Relationship between MAR & MDR: The MAR gives the address the data of the MDR will be read from or written to. Content developed by Dartford Grammar School Computer Science Department Accumulator Accumulator is connected to the data bus. Accumulator holds data that is the intermediate results of the arithmetic or logical operations of the ALU Content developed by Dartford Grammar School Computer Science Department Buses Buses are the connecting wires that connect the CPU to other devices, carrying instructions to/from components. They are normally built into the motherboard. The three most important busses are: Data bus (links RAM to CPU via MDR) Control bus (links RAM to CPU via CU) Memory bus (links RAM to CPU via MAR) Content developed by Dartford Grammar School Computer Science Department CPU block diagram Content developed by Dartford Grammar School Computer Science Department  Recap Questions 1. Describe the function of the data bus found in a PC It carries data from memory (RAM) to the MDR and then to the ALU. It carries data from the ALU to the MDR and then to Memory. 2. Outline the function of the ALU (Arithmetic Logic Unit) The ALU performs arithmetical and logical operations. It performs various calculations and comparisons using various gates Content developed by Dartford Grammar School Computer Science Department  Recap Questions 1. Describe the functions of the CU. It carries out the FDE/Machine instruction cycles. It controls the data flow between the different components. 2. Outline the function of the registers MAR and MDR. MAR- Stores the RAM/memory address of the CURRENT instruction/data to be fetched from the the RAM MDR- Stores the data fetched from the RAM or data to be written into RAM Content developed by Dartford Grammar School Computer Science Department