A+ Certification: Part 1 – Computer Hardware, System Boards, and Storage Devices

Section Objectives

After you complete this section you will:

Understand the different of drive connection type: IDE, EIDE, SCSI.

Understand what SCSI is.

Understand the different types of SCSI.

Understand what a partition is.

Understand what tape drives, CD-ROMs, and floppy drives are.

Storage Devices

There are several types of storage devices you should be aware of for the exam.

Hard Drives

There are three main types of hard drives (more specifically hard drive connection types): IDE, EIDE, and SCSI.

IDE (Integrated Drive Electronics) is the original standard for hard drives for PCs. IDE is the interface between the bus and the hard drive, based on the ISA 16-bit bus. Originally, it was designed as a separate interface, but currently most computers support EIDE with a built-in interface on the motherboard. A standard IDE drive supports up to 528 MB of space.

EIDE Connector (Click image for larger version in a new window)

The EIDE (Enhanced IDE) interface was developed to overcome the 528 MB limit on hard drive size. The most common type of connector, EIDE also supports faster access, DMA, AT Attachment Packet Interface (ATAPI) for CD-ROM and tape drives, and support for additional drives. EIDE can be added as an expansion board to older systems. Most newer systems come with EIDE functionality built-in to the motherboard.

SCSI 3 Cable (Click picture for larger version in a new window)

SCSI (Small Computer Systems Interface) is another standard for hard drive connection. SCSI also has a variety of other peripherals and storage devices which can take advantage of it.

SCSI comes in three varieties: SCSI 1, SCSI 2, and SCSI 3. SCSI 1 supports up to 8 devices, 1 of which is required to be the controller card (so you can add 7 additional devices to the controller). Unlike normal IDE or EIDE systems, most SCSI devices come in internal or external varieties and most cards can support both. SCSI 2 (also known as Ultra-2), which is more popular than SCSI 1, supports up to 16 devices (one of which has to be the adapter card or controller) and supports a higher transfer speed. SCSI 3 is sometimes referred to as Ultra-3 SCSI. Ultra-3 SCSI increases the throughput rate of the interface from 80 Mbps to 160 Mbps. The new standard for this transfer rate is referred to as Ultra160/M.

Preparing Your Hard Drive

The factory does a low level format on the hard drive prior to shipping it out which organizes the hard drive into tracks and sectors. It is possible for you to perform a low level format of a drive but highly not recommended. Low level formatting can damage a hard drive and make it unusable.

When you install a hard drive, there are several items you need to be aware of when setting it up. There are three settings on hard drives: Master/Slave/Cable Select. Master is used for the first hard drive, Slave for the second drive when you have two, and Cable Select goes in the order on the EIDE cable.

EIDE interfaces allow two drives per channel. Most EIDE controllers have a primary and secondary channel to allow for four total devices.

Before the installation of an operating system, you have to partition and format (high level format) the hard drive. When you partition a drive, you setup different virtual drives on the PC. Hard drives can have three primary partitions and 1 extended partition. Extended partitions can have up to 23 logical partitions. On most computers, you are able to setup a single partition if you wish. Commonly this becomes drive “C:” in Windows (A: and B: are typically reserved for floppy disk drives).

CD-ROMs

CD-ROM (Compact Disc – Read Only Memory) was developed by Sony and Phillips. It has a standard capacity of 650 Megabytes of information and is burned onto a disc using laser light.

CDs have expanded over the years and a typical CD-ROM today can hold 700 MBs of information or 80 minutes of music.

Most typical home machines and some business-class PCs come with a CD-R or CD-RW drive. A CD-R drive allows you to write once to a CD-R or CD-RW disc. A CD-RW drive allows you to write once to a CD-R disc or many times to a CD-RW disc.

There are many advantages to using CD-Rs and CD-RWs to store data or backup data. Cost per megabyte is very cheap on CD-Rs, most for pennies per megabyte. In addition, CD media is fairly long lasting if you care for it.

CD media can become unreadable if you leave discs in sun or heat for too long or if they become scratched.

CDFS (Compact Disk File System) is the type of filing system CD-ROMs use to store information.

Tape Backup Devices

Typical backup drives connect via the parallel port, SCSI, ATAPI, or USB ports.

There are several different competing tape formats you should be aware of. QIC (Quarter Inch Format) is a format which either comes in a 3.5” or a 5.25” hard plastic case. It can store from 40 Mb to 25 GB worth of data.

Linear Tape-Open (LTO) is an open standard format developed by IBM, Hewlett-Packard, and Seagate. LTO was developed to provide a standard among normally proprietary tape backup systems. LTO format tapes come in a variety of sizes and types.

The positive of tape is a large amount of storage for a low reusable cost. The negatives of a tape are its access time – a tape starts at the beginning and moves to the spot where the data is when retrieving information.

Tape devices are typically only used for backup situations.

Floppy Drives

In early home PCs, often the floppy drive was the only way to store and retrieve data (though in my first computer – an Atari – I had a tape cassette recorder which stored and retrieved somewhere in the neighborhood of 16K of a normal audio cassette). Over the years, the floppy drive has stayed with us, though more as a leftover from the early days than anything else.

A typical system with a floppy drive is a 3.5” drive which holds 1.44 MB.

After you have studied this section you should:

Understand the different of drive connection type: IDE, EIDE, SCSI.

Understand what SCSI is.

Understand the different types of SCSI.

Understand what a partition is.

Understand what tape drives, CD-ROMs, and floppy drives are.

Congratulations!

You have completed the A+ Hardware Service Technician: Computer Hardware, System Boards, and Storage Devices online course. You can now return to the main CompTIA Hardware course page or take the free System Architecture course here. Thanks!