SLR1 Year 13 Recap Lesson (student version).pptx

cpu and architecture 1.3 a level ocr.

1. AS Spec Point: 1.1.1a Structure and function of the processor Complete the following diagram to the best of your ability without any additional resources.

2. AS Spec Point: 1.1.1b Structure and function of the processor Name the three stages occurring here and describe what is happening. Memory Address Register (MAR) Arithmetic Logic unit Current Instruction Register (CIR) Program Counter (PC) Status Register (SR) Control Unit Memory Data Register (MDR) R6 R5 R4 R3 R2 R1 R0 External Bus Main Memory Memory Address Register (MAR) Arithmetic Logic unit Current Instruction Register (CIR) Program Counter (PC) Status Register (SR) Control Unit Memory Data Register (MDR) R6 R5 R4 R3 R2 R1 R0 External Bus Main Memory Memory Address Register (MAR) Arithmetic Logic unit Current Instruction Register (CIR) Program Counter (PC) Status Register (SR) Control Unit Memory Data Register (MDR) R6 R5 R4 R3 R2 R1 R0 External Bus Main Memory

3. fetch fetch The PC stores the address of the next instruction to be carried out. 2) This address is copied into the MAR. 3) The data of the address in the MAR is copied into the MDR. 4) The data of the MDR is copied into the CIR. 5) The contents of the PC are incremented by 1.

4. decode 6) The contents of the CIR are then translated into the binary code so the CPU can carry th e instruction out . CU understands the instruction so that the processor knows what to do next.

5. execute The address part of the instruction is copied from the CIR to the MAR. The data found in the address in the MAR is copied to the MDR. The instruction is then executed.

6. AS Spec Point: 1.1.1c Structure and function of the processor List as many factors as you can think of which could affect the performance of a CPU. Cache size,number of processors ,clock speed For each factor you listed provide a brief explanation of how / why it would affect the CPUs performance. Number of cores A will often have multiple processors, or cores on a single chip. This means more than one instruction can be executed at a time. Size o processor f the registers The CPU contains small memory spaces called registers, which store data and instructions while the CPU processes them. The size of the registers determines the amount of data with which the computer can work at a one time. RAM The more RAM a PC has, the more program instructions and data can be held in memory, which is faster than storage on disk. If a PC does not have enough memory to run a program, it must move data between RAM and the hard disk frequently. This process can greatly slow a PC’s performance.   Clock speed The computer`s system clock sets the pace the CPU by using a vibrating quartz crystal. A single "tick" of the clock is the time required to turn a transistor off and back on. This is called a clock cycle. Clock cycles are measured in Hertz (Hz), a measure of cycles per second. The faster a PC’s clock runs, the more instructions the PC can execute each second. Data bus The data bus width determines how many bits can be transmitted between the CPU and other devThe wider the data bus the more bits that can be transmitted at once, reducing the number of fetches. The speed of data transfer along the bus also affects it’s performance. ices. Cache Cache memory is high-speed memory that holds the most recent data and instructions that have been loaded by the CPU. Cache is located directly on the CPU, making it faster to access than normal RAM. Cache is made of very high speed components. Having a cache reduces the number of fetches for both instructions and data. Recently executed instructions, for example in a loop will be stored in the cache

7. AS Spec Point: 1.1.1d Structure and function of the processor Define the following types of processor architecture: Von Neumann, Harvard, Contemporary. Vonn neumann Traditional computer architecture that forms the basis of most digital computer systems. A single control unit manages program control flow following a linear sequence of “fetch-decode-execute”. Harvard A computer architecture with physically separate storage and signal pathways for instructions and data. These early machines had data storage entirely contained within the central processing unit, and provided no access to the instruction storage as data. contemporary Any modern set of disciplines that describes the functionality, the organisation and the implementation of computer systems. Most modern computer systems are contemporary in nature, that is to say the share characteristics of both Von Neumann and Harvard architectures.