1.2 memory + storage
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items stored in RAM
Random Access Memory= programs/data/operating system that’s currently in use
compare RAM + ROM
RAM= volatile, loses memory when switched off, read-write ROM= non-volatile, memory not lost when computer switched of, read-only
what is virtual memory
simulated memory written on hard drive to a file- appears to act as RAM but is secondary
why do we need virtual memory
if computer runs more programs than RAM can support, VM allows more memory to be used than in system
how is VM implemented
OS set up virtual memory using VMM. VMM creates a file oh hard disk (enough for memory needed), OS can address memory as if it were RAM, paging
what is paging (extra information)
(also called swapping) process used by OS to move data between RAM and VM. moving data when processes are not needed but copied back to RAM when needed
what is flash memory
solid state media (no moving parts, removable storage, device using flash memory)
devices that use flash memory
USB drives, memory cards, SSD cards
What are the advantages associated with using flash memory?
+durable will not break if dropped/ exposed to heat. +Very reliable as no moving parts. +V compact but can store lot of data in a small space. +V fast access time compared to a hard disk/ DVD. +Low cost and reliable. +Light weight so easily portable.
What are the problems associated with using flash memory?
Can get lost easily. Can wear out over a long time period. More expensive than CD or DVD. The metal part that is inserted into the USB port can become bent or damaged
what is secondary storage
devices are not directly accessible with CPU, not constantly connected with computer,
why is secondary needed
back up data in main memory, stores data/instructions that would be otherwise lost when switched off, for larger storage capacity
examples of external secondary storage devices (not built in)
CD, memory card, DVD, Blu-ray disk, USB memory stick, (external) solid state disk/hard disk drive
examples of internal secondary storage
Hard Disk Drive (HDD), SSD (solid-state drive)
what is optical storage’s advantages
(an example of 3 main types of secondary storage) \+inexpensive \+reliable \+robust \+ relative large capacity
one other type of secondary storage
-Magnetic Store large capacity commonly used making it possible to share compatibility can be used to store operating system and other files and programs reliable cost-effective. OR -Solid state Flexible Inexpensive faster access to data Can be used for portable devices generally smaller in size robust easy to use no setup requirements.