Computers Flashcards
What does the MAR do
Holds the memory address of the current instruction to be fetched or the address where contents of the MDR is to be stored.
What does the MDR do
Holds the data for the current instruction being decoded and executed
What does the CIR do
Holds the current instruction being decoded and executed
What does the ACC do
Stores the results of logical and arithmetic calculations, such as from the ALU by which it is used to add numbers etc.
What does the PC (program counter do)
It is incremented each time an instruction is fetched from memory and holds the memory address of the next instruction to be processed
Effect of overclocking (positive) and the drawbacks of it
More clock cycles per second therefore more instructions are executed per second
It can cause the CPU to overheat, as it is working harder, causing long term damage
How does the OS manage processes
Copies programs and data from secondary storage into memory when opened.
Uses scheduling to ensure every process gets a share of CPU time (a time slice)
Holds processes in a queue and allocates a time slice
Higher priority processes get a longer time slice
During the time slice they have exclusive use of the CPU
If process is not completed during time slice, it rejoins the back of the queue
How does the OS manage memory
Designates an area of secondary storage to be used as virtual memory when the RAM is full.
Uses a paging algorithm to decide which processes to transfer into virtual memory
When its turn to use the CPU arrives, it is swapped back into main memory
How does the OS manage users
Each user has a unique username and password controlled by the OS.
Users can be granted different levels of access to the functions of the computer.
How does the OS manage files
Allows the creation, deletion, copying, movement of files.
Allows the creation of folders and sub folders.
Can search for files.
How does the OS manage peripherals
Uses device drivers to communicate with peripheral devices such as printers
4 examples of utility software
Backup
Data compression
Defragmentation
Anti malware
