1: The CPU Flashcards
1
Q
CU
A
- Coordinates all activities of the CPU
- Directs the flow of data between the CPU and other devices
- FDE cycle happens here
- Sends memory read/write signals to main memory on the control bus
2
Q
PC
A
- Holds the address of the next instruction to be executed
- Holds a close relationship with MAR: the address held in the PC is copied to the MAR
3
Q
MAR
A
-Holds the address of the memory location from which data is to be fetched or to which data is to be written
-Sends addressed to memory down address bus
4
Q
MDR
A
- Temporarily stores the data which has been read from or written to memory
- All data to and from memory must pass through the MDR via the data bus.
5
Q
CIR
A
- Holds the current instruction being executed
- Contents of MDR are copied into CIR if it is an instruction
- Contains opcode and operands of the current instruction
- Instruction = opcode + operands
6
Q
ALU
A
-performs arithmetic and logic functions in the CPU
-ADD, SUBTRACT, MULTIPLY, DIVIDE
- AND, OR, NOT, XOR
- Binary shift
-Comparison
7
Q
ACC
A
- a general purpose register which stores results of calculations performed in the ALU as well as control information
- The more general purpose registers a CPU has, the faster it may operate
8
Q
Address Bus
A
Carries memory addresses that identify where the data is being read or written to
9
Q
Data Bus
A
Carries the binary that make up the actual information being transmitted around the CPU
10
Q
features of Von Neumann architecture
A
- Shared memory space for instructions and data
- Instructions and data are stored in the same format
- A single control unit or processor follows a linear FDE cycle
- One instruction at a time
- Registers are used as fast access to instructions and data
11
Q
Features of Harvard architecture
A
- Instructions and data stored in separate memory units
- each has its own bus
- Reading and writing data can be done at the same time as fetching an instruction
- Used by RISC processors
12
Q
How do Von Neumann and Harvard architectures differ from contemporary architectures?
A
- SIMD (Single Instruction Multiple Data): Parallel processing is where a processor carries out a single instruction on multiple data items at the same time - often used by graphic processors
- MIMD (Multiple Instructions Multiple Data), another version where multiple instructions are carried on multiple data items across several cores
- Distributed computing : Where multiple computers on a shared network each take part on part of a bigger problem
13
Q
Clock Speed
A
- measured in hertz (Hz)
- Number of FDE cycles per second
14
Q
Cache size
A
- Temporary storage of frequently used data and instructions being read to and written from
- Located on or near the CPU
- Stores copies of recent data and instructions
- Quicker to access than RAM, improving efficiency of CPU
15
Q
Number of cores
A
- A core is a complete copy of the CPU, with its own separate registers and units
- CPUs with multiple cores have more power to run multiple programs at the same time
