Computer Peripherals: Hard Drives, CD-ROMs, Monitors, Keyboards
Hard Drives
Hard drives are the primary storage units of a computer, where a large amount of data and programs are stored.
Parts of a Hard Drive
Physical Parts
- Disk: The main part of a hard disk.
- Heads: The magnetic part that reads/writes information on the HDD.
- Spindle: The part of the hard drive that acts as a support. Disks are mounted on it and spin.
- Actuator: The mechanism that moves the read/write heads.
Logical Parts
- Tracks: Invisible concentric rings along which magnetic impulses are recorded.
- Sector: Different parts into which each track is subdivided.
- Cylinder: A set of tracks that the OS can access simultaneously in each position of the heads.
- Cluster: The length of a track taken as the unit of the process.
Hard Drive Features
Access time, rotational speed, buffer size, transfer speed, interface, physical size, capacity.
CD-ROM
CD-ROM drives can read data stored on CD-ROM discs that are inserted into these units.
- DVD-R: These only allow you to record information once, after which it cannot be rewritten.
- DVD-RW (Rewritable): These allow the use of appropriate discs to be recorded numerous times.
- DVD-R/RW: Most appropriate for video. Requires an initialization process and a completion to format the disk and close the session.
- DVD+R/RW: Most appropriate for data. Does not require these two processes. Incorporates “lossless linking,” which allows you to stop recording at any time without errors.
Other Storage Devices
Up to 250MB
- ZIP (IOMEGA) – 100, 250, and 750 MB
- SuperDisk LS-120
- EZFLYER 230MB
Up to 2GB
- Magneto-Optical 3 1/2″ from 128MB to 1.3GB
- JAZ (IOMEGA) 1GB or 2GB
- SYJET (SyQuest) 1.5GB
Present Storage Devices
- Pendrive: USB flash memory drive. Inside are one or more flash memory chips, depending on their capacity, a slot for this, and an input/output connector for USB (USB 1.0, 1.1, 2.0).
- SD, xD, CF, and others: CD, MSP, SD, MSD, MMC, MMMC, SM, xD.
Monitors
Monitors are the medium through which visual information is presented to the user. The main and only function is to allow the user to interact with the computer.
Size/Resolution
The number of pixels that the screen contains. Frequency is measured in hertz and is the number of times per second that the display is scanned.
Types of Monitors
CRT, LCD (DSTN and LCD), Plasma, Touch.
Keyboards
Keyboards are input devices, being the most common peripheral for entering data into the computer. Common layouts include QWERTY and Dvorak.
83/84 Keys
Writing area, number pad section, function keys.
101/102 Keys
Writing area, number pad section, function keys, screen controls, and cursor section.
Membrane Keyboards
These use four layers. They are cheaper than mechanical keyboards, are sealed, and are ideal for harsh environments.
Mechanical Keyboards
These use a small spring located beneath each key to return it to its original position when no longer pressed.
Mice
Mice are input or pointing devices that allow us to manage and control the movement of the cursor on the screen.
Printers
Printers are output devices that present information on paper.
Types include impact printers (matrix), thermal printers, inkjet printers, and laser printers.
Scanners
Scanners are input devices. Their function is to digitize images such as photographs.
Types include handheld scanners, roller scanners, and flatbed scanners.