topic 4 - operating system & computer architecture
No description yet. This curated deck is ready for daily study.
Card preview (12)
what does an operating system do? (6)
• loads software • Manages hardware • Manages error handling • Manages user accounts • Allows multitasking • Provides an interface
how does interrupt work (4)
• A signal sent to the processor • Requests processor time • Processor stops to service interrupt • Interrupts have different priorities
name 3 devices that use interrupt
• Printer • Keyboard • Mouse
name the 3 buses
• Control bus • Address bus • Data bus
what does a Control bus do (3)
• Carries signals • Directs the CPU • Can be unidirectional or bidirectional
what does an Address bus (2)
• Carries address locations of next item to be fetched - Data travels one way ( unidirectional)
what does a Data bus(2)
• Carries data that is being processed - Data travels in both directions (bi-directional)
name the 5 registers used
• PC; Program Counter • MAR; Memory address register • MDR; Memory data register • CIR; Current instruction register • ACC; Accumulator
role of the control unit (4)
• Controls operation of memory, processor and input/output • Fetches each instruction in turn • Interprets instructions • Sends signals to other components telling them what to do
role of the ALU (arithmetic logic unit) (3)
• Carries out calculations • Carries out logic operations • Holds values during calculations in a register called an accumulator (ACC)
explain the stored program concept
• Programs / instructions are stored in memory • Data is stored in memory • Instructions are fetched and executed one after another
explain how execute fetch system operates (6)
• PC has address of next instruction to fetch • PC copied to MAR via address bus • Instruction copied from memory to MDR • Instruction copied from MDR to the CIR • Value in PC incremented to point at next instruction to fetch • Address of instruction placed in MAR Instruction decoded and executed