chap 2: storage units

Question 1

what is the function of storage

Answer 1

• reads, writes, retains data
• classified as primary and secondary, or temporary and permanent

Question 2

RAM

Answer 2

• primary storage
• integrated circuits made up of transistors + capacitators, stores bits
• data + apps opened stored in RAM
• cache: small area of very fast RAM; stores instructions used repeatedly, reduces instruction loading time
• instructions on the cache only needs to be loaded onto cache once
• expensive, fast, commonly used

Question 3

DRAM

Answer 3

• dynamic RAM
• composed of transistor + capacitor per cell
• capacitors: electrons escape therefore constant recharging needed
• constant recharging = time = decrease in performance
• makes up normal RAM

Question 4

SRAM

Answer 4

• static RAM
• able to hold binary state without recharging
• much faster than DRAM
• uses flip-flops: circuits that include feedback to enable them to maintain a particular state(once it stores a bit, it is stored until it is replaced with the opposite value)
• expensive + faster, therefore used for Level 1 + 2 cache memory

Question 5

virtual memory

Answer 5

• when physical RAM is exhausted, virtual memory is deployed
• virtual memory: allowing the system to remain operational with reduced performance, accessing hard drive to make up for shortage of RAM

Question 6

hard disks

Answer 6

• secondary storage
• disk + magnet, stores positive and negative magnetic data through electrical charge
• volatile
• hard disks cheaper than SSDs per storage unit, but slower

Question 7

SSD

Answer 7

• secondary storage
• solid state drives
• expensive, fast, volatile
• unable to recover lost data
• stored/installed in racks
• wears out easily - physically
• replacing hard disks slowly but surely
• not sequential

Question 8

tapes

Answer 8

• secondary storage
• cheapest storage per byte
• uses magnetic signals
• sequential, magnetic storage
• very slow

Question 9

CD

Answer 9

• secondary storage
• compact disk
• non-volatile, info stored with laser
• used through reflection of light off the surface

Question 10

ROM

Answer 10

• primary storage
• stores permanent instructions required constantly by a device

Question 11

registers

Answer 11

• primary storage
• temporary stores for data during processing
• located in CPU
• must be very, very fast
• delays = major performance problems

Question 12

flash memory

Answer 12

• electronic, solid-state, non-volatile
• flash drives, removable storage
• traps electrons to store data, even when no power is present
• solid state: no moving parts
• fast, silent, reliable, expensive!!