Memory
•Two type of storage: primary
and secondary.
•Primary storage = “memory,” “main
memory,” “RAM”; this type of memory is temporary and volatile.
•Secondary storage = hard
disks and
flash memory units; this type of memory is relatively
permanent and nonvolatile.
Memory Chips Explanation
RAM Random Access Memory chips are volatile and hold:
sSoftware
instructions
sData
before & after the CPU processes it
ROM Read Only Memory
sCannot
be written on or erased without special equipment
sAre
loaded at factory with fixed (permanent) start- up instructions (BIOS), that
tell the computer how to load the operating system
CMOS Complementary Metal Oxide
Semiconductor
sPowered
by a battery
sContains
time, date, calendar, boot password
Flash Nonvolatile memory that can be
erased and reprogrammed more than once
sDoesn’t
require a battery
sUsed
in newer PCs for BIOS instructions
Speeding up Processing: Cache
•The CPU works much faster than RAM, so it
often must wait for information
•Cache
temporarily stores instructions and data that the processor uses frequently to
speed up processing
•Level 1
cache is part of the microprocessor
•Holds 8 to 128
KB
•Faster than Level 2 cache
•Level 2
cache is external cache
•Holds 64 kb to 16
MB
•Level 3
cache is on the motherboard
•Comes on very high-end computers
•Holds 2 to 8 MB
•Virtual Memory—also
used to speed up processing.
•This type of memory is unused hard disk
or optical (CD) space that the processor uses to extend the capacity of RAM.
•The processor goes first to L1 cache,
then L2 cache, then RAM, then virtual memory.
Each
type of memory is slower than its predecessor.
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