Topic 7 Flashcards
What is a backing store?
A non-volatile storage device
What does a power supply do?
Converts alternating current to low-voltage direct voltage
Name four tasks the processor is responsible for?
Sorting and searching data
Performing calculations
Logical decision making
Control of input, output and storage devices
What is the bus system is composed of?
The bus system is composed of the communication links which connect the various parts of the computer
What are the 3 buses?
Address bus
Data bus
Control bus
Draw the bus diagram
xxx
What does the main memory do?
Main memory stores program instructions and data that are processed by the processor
What does the address bus do?
The address bus specifies a physical address in main memory and the value that is to be read or written into that address is communicated via the data bus
What does the control bus do?
the control bus manages data processing; for example, sends a signal to either write from the data bus to a memory address or a signal to read data from a memory address
Input and output - ______ _______ received from the _______ include input (read) or _____ (_____) requests. These control signals are the used to connect a ______ bus to specific I/O devices.
PROCESSOR WRITE CONTROL SIGNALS OUTPUT SYSTEM
Input and output - control signals received from the processor include input (read) or output (write) requests. These control signals are the used to connect a system bus to specific I/O devices.
What is Von Neumann’s architecture?
Data and instructions are both stored in the main memory
Draw the Von Neumann architecture
What is Harvard architecture?
Draw Harvard architecture
xxx
What is addressable memory
What is addressable memory
Why is addressable memory used?
the processor needs to be able to locate memory locations so each location is given a code
How does the processor locate a memory location?
- The processor writes the code into the address bus
- The processor sends a request to the control bus with instructions to read or write to the memory location
- The data that is being read from or written to will be transferred via the data bus
What is the stored program concept?
Data and instructions are both stored in the main memory
What is Harvard architecture?
data and instructions are stored separately
What does the ALU do?
Performs mathematical and logical operations
What does the control unit do?
Fetches instructions, decodes them, and executes
What does the clock do?
Synchronises computer operations
What does the register do?
Used to hold instructions and data temporarily
What are general purpose registers used for?
Used to hold instructions and data temporarily
What does the ACC register do?
Used as fast temporary storage by the ALU
What does the SR register do?
The status register is a hardware register that contains information about the state of the processor
What does the PC register do?
Holds the address of the next instruction to be used
What does the MAR register do?
Holds the address of the current instruction being executed
What does the MBR register do?
Holds the instruction from the (MAR) and the associated data
What does the CIR register do?
Used to store the instruction that is to be decoded and executed
Explain the ‘fetch’ part of the ‘fetch, decode, execute cycle’?
The PC points to the next instruction to be fetched
The contents of the PC are copied into the MAR
The contents of the MAR are transferred by the data bus to MBR
The contents of the MBR are copied to CIR
the PC is updated to the address of the next instruction
Explain the ‘decode’ part of the ‘fetch, decode, execute cycle’?
The instruction in the CIR is decoded
Explain the ‘execute’ part of the ‘fetch, decode, execute cycle’?
The decoded instruction is executed
The process is repeated
What is the op-code?
Op-code is machine code instructions
What is the operand
Is the value or memory address
In a 16-bit operation, how many bits represent the op-code?
4 bits for the op-code
12 bits for the operand
.
.
What is direct/absolute addressing?
The code refers to a memory location
e.g
ADD (1302)
It adds the contents of address 1302 to the accumulator
Why does assembly language exist?
It is used to make machine code easier to remember and read
what does a # mean
LDR r1, #21
Loads THE NUMBER into the address r1
