1.1 The characteristics of contemporary processors, input, output and storage devices Flashcards
1.1.1 structure and function of the processor
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what does the arithmetic and logic unit do
The ALU completes all the arithmetical and logical operations
what is the control unit
the control unit is a part of the processor which directs operations inside the CPU
what are registers
small memory cells that operate at high speeds
-pc
-acc
-mar
-mdr
what does the program counter (PC) do
the program counter holds the address of the next instruction
what does the accumulator do? (ACC)
temporarily stores the results of calculations performed in the ALU
what does the memory address register (MAR) do
holds the address of a location that is to be read from or written to (memory)
what does the memory data register (MDR) do
Temporarily stores data that has been read
or data that needs to be written (to memory)
what does the current instruction register (CIR) do
Holds the current instruction being
executed, divided up into operand and
opcode.
what is a bus
a set of parallel wires which connect two or more components together
what is the address bus used for
-one way bus
used to transmit the memory addresses specifying where data is to be sent to or retrieved from
what is the data bus
a two-way bus used to transport data and instructions between components
what is the control bus
a two-way bus used to transmit control signals between internal and external components.
what is von neumann architecture
architecture in which there is a single shared memory and shared buses for both data and instructions
advantages and disadvantages of von neumann architecture
ADV:
-Cheaper to develop as the control unit is
easier to design
-Programs can be optimised in size
DIS:
-slower
what is harvard architecture
architecture in which there are two seperate memory and seperate buses for data and instructions
advantages and disadvantages of harvard architecture
ADV:
-Quicker execution as data and instructions can be fetched simultaneously
-Memories can be different sizes, which can
make more efficient use of space
DIS:
-costly
-complex
von neumann and harvard comparrisons
-Von Neumann uses a single memory for both instructions and data, while Harvard uses separate memories.
-Von Neumann fetches instructions and data sequentially, whereas Harvard fetches them simultaneously.
contemporary processor
Contemporary processors use a combination of Harvard and Von Neumann architecture.
Von Neumann is used when working with data and instructions in main memory, but uses
Harvard architecture to divide the cache into instruction cache and data cache.
