Exam 3 Flashcards
MMU
Memory Management Unit
TLB
Translation Lookaside Buffer
FIFO
First In, First Out
DMA
Direct Memory Access
RAID
Redundant Array of Inexpensive Disks
dynamic relocation
moving things around in memory dynamically
swapping
Memory allocation changes as processes come into memory and leave it
memory compaction
“burping” the holes out from between the pages
coalescing
combining adjacent holes in RAM into one
virtual address
this can be added to the block’s base to get the physical address
page frame
block in REAL memory that may hold a page
page fault
an error that occurs when a block of memory that has not been stored in RAM has been attempted to be accessed
page table
An array with subscripts that correspond to blocks of virtual memory. The destination block of real memory is the value of that subscript. So array[virtualMemoryBlock] would hold the actual physical RAM address
translation lookaside buffer(TLB)
a small hardware device that maps virtual address to physical addresses without going through the page table
dirty page frame
when a page in RAM and a page on the disk differ (variables changed, etc)(One that has been modified)
working set
the set of pages that have been accessed in the k most recent
thrashing
excessive page files
cylinders
vertical sections of the piece of the disk
sectors
pieces of the track
cycle stealing
disk drives have higher priority than the CPU and will steal cycles from it on the bus
tracks
a piece of the surface of the disk
striping
when a file is spread across multiple disks
cylinder skew
starting point for next larger track is offset from previous track, to account for time required for read/write head to move so it doesn’t have to wait for a complete revolution for start point to come back again
elevator algorithm
goes up to the top, and down towards the bottom, picking processes as it goes up and down
pits and lands
burning mountains and valleys on the surface of the cd to represent 1s and 0s
mickey
unit of mouse movement
pixel
a picture element
i-node
an index node, stores the attributes and disk block locations of the filesystem object’s data
in order to support multiprogramming with dynamic relocation, computer designers added what two special registers?
Base register and the limit register
what data structures may be used to keep track of which sections of memory are used by a process and whech sections are holes
Bitmap, Linked List
how would these structures be used to coalesce memory
bitmap-there’s nothing to do
linked list-take two nodes and merge them into one
what is the difference between a page and a page frame?
page - virtual page
page frame- where it goes in real memory
who or what deals with page faults
OS
what is stored in a page table
the mapping between virtual and physical addresses
Why is a translation lookaside often used?
speeds up the process of checking to see if a page has been loaded in memory
what is an inverted page table and when might it be used
When subscripts and values are swapped. Subscripts = page frames and values = page
what is the formula that determines the optimal page size?
p=sqrt(2se)
what are the two types of backing stores
executable image
page file
what is a platter
a circular disk - a track on top and a track on bottom
a track
a ring of sectors on a disk
a cylinder
a vertical group of platters
a sector
a section of space in a track
what is seek time
how much time it takes the read/write head to get to its destination
what is rotation time or rotational delay
how long it takes for a sector to make it all the way around to its origin point
describe the 6 RAID levels
0-striping; no parity; purely parallel and for speed
5-duplication across drives with parity bit, which is also shared by other drives so it’s shared uniformly
6-duplicated parity bits
the time required to read or write a disk block is determined by what three factors?
seek time
rotation delay
transfer time
explain how 24-bit RGB representation is used to render “true color”
One byte for Red, one for Green, one for Blue
what would a system manager implement disk quotas?
keep anyone from hogging space
what two techniques are often used to track the free blocks on a disk drive
bitmaps
link list
