A+ 220-701 Exam Objective
Objective 1.1: Categorize storage devices and backup media
Key Points
Today you learn the names, purposes, and characteristics of storage devices. Today is the first of many challenging days. It does get easier. The internal devices have many details, all of which are fair game on the CompTIA A+ exam. Faced with entering a cold swimming pool, a running-start, closed-eye, tucked-knee cannonball is a great way to get in the water (and impress your friends). So, take a big breath and hold your nose.
Storage Devices
Storage devices include hard drives, floppy drives, nonvolatile random-access memory (NVRAM), tape drives, optical drives (CD and DVD drives), flash drives, and network drives.
Hard Drives
The hard disk drive (HDD) has been a mainstay of PCs for a long time. Because of its widespread use, it is a big part of the A+ exam. Traditionally, the HDD stores the operating system and the bulk of data in the PC. It is mounted in a 3.5-inch bay, and connects internally through a parallel advanced technology attachment (PATA) channel. PATA interfaces are sometimes referred to as advanced technology attachment (ATA) or integrated drive electronics (IDE). Jumpers are used to determine the HDD’s designation as master, slave, or cable select.
Most new PCs use a controller called serial ATA (SATA) for HDD and optical drives. SATA does not use jumpers or designations. Instead, SATA uses one header and one cable per drive.
All HDDs work the same way. Arms move read/write (R/W) heads over the surface of spinning magnetic platters. These R/W heads either align molecules to create a positive charge (a 1) or leave it with a neutral charge (a 0), thus making the binary code. When reading, the heads float above the disks and feel the positive charges or no pull from the neutral.
Floppy Drives
Incredibly, this is still on the exam. Luckily, there are just a few things to know about them. In many ways, a floppy disk drive (FDD) is like an HDD. It spins a disk, moves R/W heads across the surface, and stores data magnetically. There are two important differences: Capacity is limited to 1.44 MB, and the disk is removable by the end user. They mount in 3.5-inch bays that have access to the outside of the case.
A classic A+ question involves an FDD status light that stays lit all the time. The cable is oriented backward. Turn off the PC, unplug the FDD cable from the drive, flip it over, and plug it back in. Normally, the colored wire on the ribbon cable (pin 1) is closest to the Berg power connector. On the motherboard end, it should be oriented based on the numbers printed around the FDD cable header. Because there are 34 wires in an FDD cable, it is narrower than a PATA ribbon.
Solid-State HDD and NVRAM
Ranging from small external universal serial bus (USB) devices to larger-capacity HDDs, solid-state drives are in reality NVRAM storage devices. NVRAM, often referred to as flash memory or flash RAM, is slower than RAM but still faster than traditional magnetic storage media. Unlike RAM, NVRAM can maintain its data when not powered. Solid-state drives are especially good for laptops where portability, performance, durability, and low power consumption are valued over price and drive capacity.
Tape Drives
A magnetic tape is drawn across stationary R/W heads, but the same magnetic process takes place. The tape is removable by the user, but the drive remains mounted and connected to the PC. Tape capacity is large, comparable to HDDs, but access time is slow because of the sequential nature of tape media. These are primarily used as server backups.
CD, DVD, and BD Drives
The basic optical drive is a compact disc read-only memory (CD-ROM). This CD-ROM drive reads premade discs and cannot write (burn) CDs. The CD can hold 650 MB or 700 MB of data. The CD-ROM drive mounts in a 5.25-inch bay and connects to the motherboard via a PATA or SATA interface.
Digital versatile disc (DVD) has many more variations. The basic read and write letters still apply, but there are two formats: + and –. For our purposes, they are the same. Just note that they are not compatible with each other. Plus drives only read/write plus CDs. Newer +/– hybrid drives can read and write both. Generally speaking, DVD drives are backward compatible and can use CDs. A typical DVD holds 4.7 GB of data or 8.5 GB for double layered (on the same side). Blu-Ray disks (BD) can hold up to 50 GB of data. A Blu-Ray disk can contain 25 GB for a single layer and 50 GB for double layer.
Optical media that is designated RW means it can be rewritten. If it is labeled with just an R that means once it is “burned” it cannot be changed.
Table 31-1 compares CD, DVD, and Blu-Ray drives.
|
CD Family |
DVD Family |
Blu-Ray Family |
Need to Know |
|
CD-ROM |
DVD-ROM |
BD-ROM |
Can only read premade discs. |
|
CD-RD |
DVD+/–R |
BD-R |
(Recordable) Write a disc once, and it is read-only after that. |
|
CD-RW |
DVD+/–RW |
BD-RE |
BD-RW (Rewritable) Read and write a discrepeatedly. |
|
CDRAM (not an optical drive) |
DVD-RAM |
("Endlessly" rewritable) Used primarily as surveillance-camera footage. |
Network Drives
These drives are often referred to as remote, shared, or mapped drives. This means that the storage device resides on another computer, server, or other network device, not on the end user’s (local) PC.