computer science 0.0 / 5 ? ICTictGCSEOCR Created by: lewis123terryCreated on: 25-04-18 13:09 what is the purpose of the CPU? executes program instructions, performs calculations and comparisons. 1 of 14 what are the 4 components of von neumann archetechture? memory address register (MAR), memory data register (MDR), program counter (PC) and accumulator. 2 of 14 what is the purpose or the memory address register (MAR)? stores the location to be accessed next. data will either be read or written to it. 3 of 14 what is the purpose of the memory data register (MDR)? stores the data itself that has either just been read from memory or is about to be written to it. 4 of 14 what is the purpose of the program counter(PC)? contains the memory location of the next instruction to be accessed between instructions, the contents of this register are incremented. 5 of 14 what is the purpose of the accumulator? it stores the results of the calculations performed by the ALU. 6 of 14 what is the http? and what does it stand for? hyper text transfer protocol. used by we browsers to access websites and communicate with web servers 7 of 14 what is the IMAP? and what does it stand for? internet message access protocol. used to retrieve emails from a server. used by most most we based email clients. 8 of 14 what are the 4 layers? layer 1-data link layer, layer 2-network layer, layer 3-transport layer, layer 4-application layer. 9 of 14 what does layer 1 do? passes data over physical network. it is responsile for how the bits are sent as electrical signals over cables, wireless and other hardware. 10 of 14 what does layer 2 do? makes communications between networks, directing data packets and handling traffic. used by routers. 11 of 14 what does layer3 do? controls data flow e.g. splitting data packets and checking packets are correctly sent and delivered. 12 of 14 what does layer 4 do? turns data into websites and other applications and vice versa. 13 of 14 why use layers? Breaks down communication in to manageable chunks. 14 of 14
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