Section 5: Computer Organisation and Architecture Flashcards
Chapter 25:
What are the three main busses in a computer?
Control Bus.
Data Bus.
Address Bus.
Chapter 25:
What are the six main components of the CPU?
Control Unit. (CU) Arithmetic Logic Unit. (ALU) Registers. Cache. Busses. Clock.
Chapter 25:
What does the Control Unit do?
Coordinates and Controls all operations carried out by the computer.
Follows the Fetch-Decode-Execute Cycle.
Chapter 25:
What does each stage of the Fetch-Decode-Execute Cycle do?
Fetch:
Causes the next instruction to be fetched from main memory.
Decode:
Decodes the instruction.
Execute:
Runs the instruction.
Chapter 25:
What are the two types of operation that the ALU can perform?
Arithmetic.
Logical.
Chapter 25:
What are Arithmetic operations in the ALU?
Deal with values.
Add.
Subtract.
Multiply.
Divide.
Chapter 25:
What are Logical operations in the ALU?
Deal with comparisons and switches.
NOT. AND. OR. XOR. NAND. NOR. XNOR. Buffer. & Shifts.
Chapter 25:
What are Registers?
Memory cells that operate at very high speeds, due to the small distance to travel; being inside the CPU.
Chapter 25:
What is a bus (in a computer)?
A set of parallel wires (“lines”) connecting two or more components of a computer.
Speed measured in Megahertz (MHz).
Chapter 25:
What do the Address Bus, Data Bus, and Control Bus do?
When the CPU wants to access a particular memory location, a signal is sent down the Address Bus to the main memory.
The data will then be transferred either from Memory to the CPU, or from the CPU to Memory. The data is transferred across the Data Bus.
The Control Bus carries commands to, and status reports from other hardware devices. The Control Bus also carries Clock Pulses, which help to keep the system under control and stop conflicts (queue transfers).
Chapter 25:
What is the “size” or “width” of a bus?
How many bits can be transferred at once. (How many lines it has)
64-bit computers have 64-bit bus widths.
Chapter 25:
A Bus is a collection of wires. What are these wires called?
Lines.
Chapter 25:
Are the following busses Unidirectional or Bidirectional?
Address Bus, Data Bus, Control Bus
Address Bus = Unidirectional.
Data Bus = Bidirectional.
Control Bus = Bidirectional.
Chapter 25:
What are Address Busses, Data Busses, and Control Busses known collectively as?
The System Bus.
Chapter 25:
What is a transmission medium?
Give an example of a transmission medium in a computer?
Where something can mediate the propagation of signals. (Sync signals to avoid collisions).
Busses are an example.
Chapter 25:
Control Busses have 7 Control Signals. List them.
Memory Write: causes data on the data bus to be written to a specified location.
Memory Read: causes data from a specified location to be placed into the data bus.
Interrupt Request: indicates that a device is requesting access to the CPU.
Bus Request: indicates that a device is requesting access to the Data Bus.
Bus Grant: indicates that the CPU has granted access to the Data Bus.
Clock Pulse: used to synchronise operations.
Reset: initialises all components.
M(WR) I B(RG) C R
Chapter 25:
How does the width of the Data Bus effect the overall system performance?
Data Bus is typically made of 8, 16, 32, or 64 lines.
When a 64-bit instruction needs to be sent down a 32-bit Data Bus, the instruction needs two calls to be sent.
This involves splitting the instruction up, as well as sending double the transmissions.
Chapter 25:
Memory is divided up internally into units.
What are these units called?
Typically how large are they?
Words.
Typically 8, 16, 32, or 64 bits in size.
Different CPUs use different sizes.
Chapter 25:
Which System Bus determines the maximum possible memory capacity of a computer system?
Why?
The Address Bus.
The Address Bus cannot map one combination of its bits to more than one memory location.
Chapter 25:
What is the maximum theoretical memory capacity of a 64-bit PC?
16,777,216 TiB (Tebibytes)
2^64 (B) /1024 (KiB) /1024 (MiB) /1024 (GiB) /1024 (TiB)
Chapter 25:
What is the maximum theoretical memory capacity of a 32-bit PC?
4 GiB (Gibibytes)
2^32 (B)
/1024 (KiB)
/1024 (MiB)
/1024 (GiB)
Chapter 25:
What is an I/O controller?
A device that interfaces between an input or output device, and the CPU.
I/O controllers are unique to the input/output device.
Chapter 25:
How does an I/O controller connect to the CPU?
Via the control bus.
Chapter 25:
How are instructions send from the CPU, through the I/O controller, into the device?
CPU sends and input/output request to the I/O controller.
The I/O controller receives this, and sends device-specific control signals to the device. It also manages the data flow to and from the device.