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Advantages of CISC
Quicker to code programs
The complier has very little work to do to translate a high-level language statement into machine code
Because the code is relatively short, very little RAM is required to store the instruction
Advantages for RISC
The hardware is simpler to build with fewer circuits needed for carrying out complex instructions
Because each instruction takes the same amount of time, i.e. one clock cycle, pipelining is possible
e.g. 4 instructions execute same speed as CISC instruction
RAM is now cheap, and RISC use of RAM and software allows better performance processors at less cost
Disadvantages of CISC
Many specialised instructions had to be built into the hardware
Only 20% of specialised instructions are used in the average program.
What do multicore processors do?
distrubute
Supercomputers have ______ of cores
thousnds
What type of problems are supercomputers used for?
Used on problems such as weather forcasting
What is a coprocessor?
What is a GPU
a specialised electronic circuit which is very efficient at manipulating computer graphics and image processing
What does a GPU consist of
t
What is the function of the GPU
A GPU is a coprocessor..
Components of the CPU
Control Units
Buses
Arithmetic-Logic Unit
Dedicated Registers
What does the Control Unit do?
The part of the processor that coordinates the activity of all other components.
•Directs the flow of data between CPU and other devices
How are Control signals sent
They’re sent along the control bus between the control unit and the other components of the computer
What is a bus?
•Buses in a computer consist of a series of connectors that transfer signals between two or more internal components
What does a system bus consist of?
Control signal/bus
Data Bus
Address bus
What is a system bus
a shared transmission medium where one device can transmit along the bus at any one time.
What is the Control bus and what is it’s purpose?
Control Bus is bi-directional – signals carried out in both directions
Purpose of the control bus is to:
•Transmit command
•Timing
•Specific status information between system components
What does the control signal include.
•Memory read: causes data from the addressed location in RAM to be placed on the data bus
•Memory write: causes data on the data bus to be written into the addressed location in RAM
•Bus request: indicates that a device is requesting use of the data bus
•Bus grant: indicates that the CPU has granted access to the data bus
•Clock: used to synchronise operations
•Interrupt: indicates a device is requesting CPU access.
What is a data bus?
The data bus is bi-directional as data can be sent both ways along the bus
Moves instructions between system components
What is the width in the data bus defined by?
the number of wires or lines it contains
What is the address bus?
•Address Bus transmits the memory addresses of words used as operands in program instructions
•Memory is divided internally into units – words
•Words is a fixed size group of digits, typically 16, 32 or 64 bits – handled as a unit by processor
•Each word in memory has its own specific address
•Data can be retrieved and sent back to processor
•Instruction has been performed > result is stored at a particular memory location > transmitted via data bus
Note 
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