Computer System Fundamentals Flashcards
Describe the function of the address bus and its direction
The address bus carries the address of the piece of memory or I/O device to be read from or written to. It is unidirectional and data travels from the CPU to memory.
Describe the function and direction of the data bus
The data bus carries the data that is to be written or has been read from memory. It is bidirectional and carries data to or from memory.
Describe the function of the control bus
The control bus carries signals that control the actions of the computer. e.g. one line of the control bus may be the read/write line.
Describe the differences and similarities between SRAM and DRAM
DRAM: Must be constantly refreshed, inexpensive to manufacture
SRAM: Does not need to be constantly refreshed, expensive to manufacture
Similarities: Both DRAM and SRAM are volatile
Describe the differences between EEPROM/EPROM and ROM
ROMs are manufactured with the required data stored permanently on them and can never be updated. More modern types of ROM such as EPROM or EEPROM can be erased and re-programmed.
Describe the ALU and its function
The Arithmetic and Logical Unit is a component of the CPU. It carries out the mathematical functions of addition, subtraction, multiplication and division.
Describe the control unit and its function
The control unit is a component of the CPU and regulates the flow of information through the processor. It receives, decodes, stores results and manages execution of data that flows through the CPU. The control unit determines how and when data is processed and ensures that it is sent to the correct components of the computer.
Describe the function of the instruction register
The instruction register holds the instruction currently being executed.
Describe the function of the memory data register
The memory data register (AKA memory buffer register or data buffer) holds the piece of data that has been fetched from memory.
Describe the function of the memory address register
The memory address register holds the address of the next piece of memory to be fetched.
Describe the function of the program counter
The program counter holds the location of the next instruction to be fetched from memory. It is automatically incremented between supplying the address of the next instruction and the instruction being executed.
Describe what the accumulator is and its function
The accumulator is an internal CPU register and is used as the default location to store any calculations performed by the ALU.
Describe the differences between polling and interrupts. State an advantage and disadvantage for each
Polling is the process of cycling round all of the peripherals attached to the computer and asking if they required any attention.
Interrupts are a mechanism for allowing peripherals to signal the CPU when it requires attention.
Interrupts are harder to implement but are more efficient.
Polling is easier to implement but less efficient than interrupts.
Name each operating system layer from the highest layer to the lowest layer
User Interface File Management System Input / Output Memory Management Kernal
Describe the user interface (UI) layer of the operating system and its function
It allows the user to interact directly with the OS.
There are two distinct types of UI: command line interface (CLI) and graphical user interface (GUI).
The objective of a UI is to allow the user to interact with the computer. It must provide a kind of input facility (e.g. keyboard, mouse, joystick) and some kind of output facility (e.g. monitor, printer)
The UI allows the user to load and run programs and controls the interaction between programs and the user. It also allows the user to modify system settings, control system function and request information.
