Unit 1 Computer Science
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, what is a cpu? Central Processing Unit
-processor with tiny transistors and capacitors
-has number of different components = each with their own roles
different components on cpu? (5) -control unit
-buses
-ALU
-cache
-dedicated registers
whats the control unit? -part of processor
-coordinates activity of all other components
control signals are sent along ----- between the control unit along the control bus
and other components
whats a bus consists of series of connectors that transfer signals between internal components
3 types of system buses Address bus, data bus and control bus
how many lines does buses usually come in? -8
-16
-32
-64 lines
5 things Control signals include? -memory read
-memory write
-bus request
-bus grant
-clock
Control signals: memory read -causes data from addressed location in RAM to be placed on data bus (opposite
the memory write)
Control signals: memory write -causes data on the data bu7s to be written into addressed location in RAM
(opposite the memory read)
Control signals: bus requests indicates that the device is requesting use of the data bus
Control signal: Bus grant indicates that the cpu has granted access to the data bus
A-Level OCR 2026 | Study
Guide, Practice Questions,
Answers, Rationales &
Exam Review | Complete
Ethics Study Guide
Updated 2026 Questions and Answers
100% Verified Exam Prep and Comprehensive
Rationales
Included
, what is a cpu? Central Processing Unit
-processor with tiny transistors and capacitors
-has number of different components = each with their own roles
different components on cpu? (5) -control unit
-buses
-ALU
-cache
-dedicated registers
whats the control unit? -part of processor
-coordinates activity of all other components
control signals are sent along ----- between the control unit along the control bus
and other components
whats a bus consists of series of connectors that transfer signals between internal components
3 types of system buses Address bus, data bus and control bus
how many lines does buses usually come in? -8
-16
-32
-64 lines
5 things Control signals include? -memory read
-memory write
-bus request
-bus grant
-clock
Control signals: memory read -causes data from addressed location in RAM to be placed on data bus (opposite
the memory write)
Control signals: memory write -causes data on the data bu7s to be written into addressed location in RAM
(opposite the memory read)
Control signals: bus requests indicates that the device is requesting use of the data bus
Control signal: Bus grant indicates that the cpu has granted access to the data bus
