11-20 Flashcards
Ports (continued)
- Bluetooth
Short-range wireless technology used to connect many types of peripheral devices
Devices need to be paired - Firewire
Legacy port (not found in newer computers)
Can connect up to 63 devices to a single port, hot-swappable
Mostly used for digital cameras - Other ports
Ethernet (network), audio, video (HDMI, DVI, etc.)
BIOS (Basic Input/Output System)
- A program stored on a chip on the motherboard
- Used to boot the computer (i.e. load the operating system when computer is turned on)
- BIOS chip is ROM (Read-Only Memory), i.e. non-volatile
May use flash memory, which can be electrically erased and reprogrammed - Uses settings stored in a CMOS chip, which uses a battery to keep data from being erased when computer turned off
- Some modern computers use UEFI instead of BIOS
Settings can be stored on a chip, hard disk, or loaded over a network
Random Access Memory (RAM)
- Temporary (i.e. volatile) storage used by a computer to hold instructions and data while they are in use
- Also known as main memory (or sometimes just memory, though that can be a little confusing)
- Allows CPU to access much more quickly than from storage devices
- Memory boards - small circuit boards that contain memory chips
Easy to add memory to desktops - memory cards plug into slots on motherboard
Cache Memory
- CPU fetches instructions and data from RAM and stores results to RAM during the Instruction Cycle
- CPU is much faster than RAM, meaning it wastes lots of time waiting
- To improve performance, most computers use cache memory
=Very fast memory that holds some instructions and data copied from the RAM
=When CPU needs to fetch an instruction or data, the cache is checked first, and if it is there, it can be returned to the CPU more quickly
=Operating systems predict which instructions and data CPU will need and copies them from the RAM to the cache
Cache Memory (Continued)
- Cache memory capacity is normally very small (compared to RAM)
- Why? It is very expensive
-Different levels
=L1 (level 1) - fastest and most expensive, built into CPU chip (256KB - 2MB)
=L2 (level 2) - a little slower and less expensive, on a separate chip on motherboard (256KB - 8MB)
=L3 (Level 3) - slowest and cheapest, but still faster than RAM (4MB - 256MB or more)
Storage Devices
-Stores instructions and data when they are not being used
-Contents not lost when power turned off (i.e. non-volatile)
-Compared to RAM:
=Non-volatile (vs. volatile)
=Much larger capacity (usually)
=Much less expensive (per byte)
=Much slower to access
Optical Discs
-A laser beam is used to read data
=CDs (about 700 MB)
=DVDs (about 8.5 GB)
=Blu-ray discs (about 100 GB)
-Can be read-only (ROM), recordable, or rewritable
-Has become largely legacy technology
Flash Memory (Storage)
-A non-volatile form of memory that can be electrically erased and programmed
-Has no moving parts
-Very reliable and fast
-Solid-State Drives (SSDs)
=Can be used in desktop and notebook computers instead of regular hard drive
=Much more expensive (than hard drives)
=More reliable, faster to access
=Usually smaller capacities
=Used as internal storage many mobile devices
Flash Memory (Continued)
-Flash Drives (portable storage)
=Also known as USB drives, key drives, thumb drives, or jump drives
=Small, portable solid-state drives
=Can connect to a computer via a USB port (USB flash drive)
-Memory Cards (portable storage)
=Used to expand the storage of smartphones, digital cameras, and other devices
=Various types (SD, micro SD, CF, etc.)
Hard Drive (aka Hard Disk)
-The primary mass-storage device in most computers
-The primary hard drive holds the operating system (and usually other programs and data files)
-Most inexpensive type of storage device (4 TB for about $90)
-Can have very large capacities (12+ TB)
-Data stored magnetically on metal platters
-Can be internal or external
