Computer Architecture 2 Chapter 2

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cache memory Cache memory is very fast memory located near to the CPU. Data in cache can be accessed very quickly.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cache memory (cont.) When data is required the CPU looks at the cache memory first. If is not in cache it looks in main memory. Data is copied from main memory into cache then to the CPU. See the Chapter 2 animation: Cache memory.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cache memory (cont.) Cache memory is expensive so there is only a limited amount in a computer. Cache close to the CPU will be the most expensive to produce but also the fastest.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cache memory (cont.) There are three levels of cache memory: Level 1, Level 2 and Level 3. The level indicates the distance the cache memory is from the CPU. L1 and L2 memory is located within the CPU. L3 memory is on the computer’s motherboard.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cores Many processors have multiple cores. These cores can work together fetching, decoding and executing at the same time. Multiple cores can process more data at the same time, making them faster.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 Cores (cont.)

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 The CPU The purpose of the CPU is to: control the movement of data and instructions fetch data and instructions from memory decode and execute instructions

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 The CPU (cont.) The purpose of the CPU is to: perform: arithmetic operations, e.g. add and subtract logical operations, e.g. AND, NOT, OR.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 The CPU (cont.) The performance of the CPU depends upon the: processor speed bus speed amount of cache available number of processor cores.

OCR GCSE Computer Science Chapter 2: Systems architecture - 2 The CPU (cont.) Some example processor specifications: Processor L1 L2 L3 Cores Speed Core i7-4940MX 256KB 1024KB 8192KB 4 4000Mhz Core i7-4960HQ 6144KB 3800MHz Core i7-6567U 128KB 512KB 4096KB 2 3600MHz Core i5-6440HQ 3500MHz Core i5-6267U 3300MHz Core i5-4288U 3072KB 3100MHz Core i3-3220