S1 - 1 processor components Flashcards
how many components does the CPU have?
The CPU has 4 components
Name all the components of the CPU
+ control unit
+ arithmetic logic unit (ALU)
+ buses
+ dedicated registers
what does the control unit do?
+ coordinates all activities of the CPU
+ directs flow of data between the CPU and other devices
+ Accepts the next instruction, decodes it, handles its execution and stores the resulting data back in memory or registers
+ Sends memory read and write
requests to main memory on the
control bus,as well as other
command and control signals such as
bus requests,bus grants,interrupt
requests ,etc.
+ Makes extensive use of the status
registers and clock.
+ .Coordinates and communicates with
all parts of the CPU (orange lines).
what does the program counter do?
. Holds the address of the next
instruction to be executed.
- This could be:
+ the next instruction in a
sequence of instructions;or
+ the address to jump to if the
current instruction is a
command to jump or branch-
this would be copied from the
current instruction register.
+ Has a very close relationship with
the memory address register. At the
start of every new fetch-decode
execute cycle,the address held in
the PC is copied to the MAR.
what does the program counter do?
Holds the address of the next
instruction to be executed.
- This could be:
+ the next instruction in a
sequence of instructions
+ the address to jump to if the
current instruction is a
command to jump or branch-
this would be copied from the
current instruction register.
+ Has a very close relationship with
the memory address register. At the
start of every new fetch-decode
execute cycle,the address held in
the PC is copied to the MAR.
how many registers are there?
there are 3 data registers
what are the 2 data registers?
+ Memory data register (MAR)
+ Memory address register (MDR)
+ current instruction register (CIR)
what does the memory address register do?
The memory address register holds the address of the memory location where an instruction or data which would be fetched or written.
And it sends these addresses to memory down the address bus
what does the memory address register do?
The memory address register holds the address of the memory location where an instruction or data which would be fetched or written.
And it sends these addresses to memory down the address bus
what does the memory data register (MDR) do?
The memory data register temporarily stores the data which is read from or written to memory.
why is the memory data register (MDR) important?
ALL DATA to and from memory MUST travel down the data bus and pass through the memory data register (MDR)
The memory data register is also known as…
the memory buffer register (MBR), its nicknamed “the gateway to the processor”
what does the current data register do?
+ holds the current instruction being executed
+ The contents of the MDR are copied to the CIR if its an instruction
+ contains the opcode + operands
what does the ALU do?
The ALU performs arithmetic and logical operations on data
what are the arithmetic operations the ALU can perform?
The ALU can perform arithmetic operations on fixed and floating numbers such as - ADD, SUBTRACT, MULTIPLY and DIVIDE.
