role of the OS Flashcards
how does the OS track location of the programs within the RAM
using binding - keeps track of where the program is in the RAM
what is logical address
reference to a stored value
need to be converted to physical address
what is physical address
actual address of one memory cell
what is address binding
mapping a logical address to a physical address
what is swapping
mechanism in which a process or blocks of code are temporarily swapped out of the RAM and into a hard disk and then later brought back into the RAM to continue with their execution
what is paging
underlying mechanism of virtual memory implementation
what does paging allow
allows modern OS to utilize secondary storage (greater in size) as if it was the primary memory
how does paging work
when the OS requests data from the disk, it swaps out a quota of data from the RAM with a quota of data on the hard disk
what can excessive paging lead to
thrashing which would lead to poor performance
where is slicing used
used by multitasking systems, multiaccess systems
what is time-slice
time allocated to each user in a multiaccess system or time allocated to a program in a multitasking system
what is the interrupt scheduler
allows the OS to switch between processes when the time slice expires
what is the scheduler
mechanism used to choose the next process to be run after each time slice ends
what is preemptive scheduling
when a high priority task takes over from the low priority task currently running
what is polling
periodic checking of devices by a central device to sample their status
CPU periodically checks each actuator, register, sensors to see if its functioning properly
how is a dedicated OS created for each device (2 methods)
take an existing OS and adapt it for the particular device
design a new OS that will fit the needs of that device
what is an advantage of taking an existing OS and adapting is to fit the needs of particular device
end users deal with familiar interface
what is a disadvantage of taking an existing OS and adapting is to fit the needs of particular device
final product won’t be optimized for its purpose
advantage of designing a new OS
it will be optimized for the purpose of the device
disadvantage of designing a new OS
takes more time, costly
