1. Hard Drive Technologies
Unit 8
Hard Drive Technologies

2. The disk surface is divided
into tracks.
Disk drives are still the primary means of storing and transporting programs and data. The vast majority of personal computers have both a hard drive and a floppy drive. As we have seen, the main attraction of the floppy drive is its portability. By contrast, the hard drive is vastly larger in storage capacity and much faster. It has to be because it holds the operating system, your application programs, and your data files.
On both the floppy disk and the hard disk, the data is stored in a number of concentric rings on the surface of the disk. Each ring is called a track.

3. Most Hard Drives Have Multiple Platters
Platter1, Track1
Platter2, Track1
Platter3, Track1
Platter4, Track1
While floppy disks have a single platter, most hard drives have multiple platters. Here four different platters are stacked one above the other. Thus, there are eight different track 1’s all lined up, one above the other. Four of them are shown here. The other four are on the undersides of the platters.

4. The eight track 1’s are referred to collectively as “Cylinder 1.”
These eight track 1’s are referred to collectively as “Cylinder 1.” In the same way, all the track 2’s line up to form “Cylinder 2,” and so forth. On hard drives of this type, there are as many cylinders as there are tracks.

5. Read\Write Head Platter
Data is written to and read from these cylinders. A side view of the platters and read/write heads illustrates how this is done. Here eight read/write heads are suspended on five arms to cover both sides of four platters. Thus, eight bits of data can be written or read at any given time.

6. This view shows how the arms position the heads on the surfaces of the platter.

7. By rotating the arms through a small arc, the heads can be quickly moved to any track. And because the disk is rotating 60 times each second on the slowest drives, every point on the surface can be quickly accessed. Newer drives can rotate at 120 times per second (7200 rpm) or even a bit higher.

8. As with the floppy, the tracks are further subdivided into sectors.
One Sector =
512 Bytes

9. Another term you will hear in connection with disk drives is the cluster. A cluster consists of one or more sectors. In the example shown here, the cluster consists of four sectors or 2 K Bytes.
Cluster

10. Cluster
The smallest unit of disk space that the OS can allocate to a file.
It consists of one or more sectors.
Generally, the larger the disk drive, the more sectors per cluster.
The significance of the cluster is that it is the smallest amount of disk space that an OS can allocate to a file. The cluster is always at least one sector and for modern drives it consists of from four to sixty four sectors. Larger drives tend to have larger clusters. In some drives this can be down-right wasteful.

11. Hard Drive Interfaces

12. ST-506/ESDI Interface
ST-506 was the first widely used drive interface technology. ESDI was a later, faster, and better technology. They share many characteristics, including the fact that they are obsolete and you may not ever see them. ST-506 and ESDI used the same cabling setup. This cabling scheme was notoriously unreliable. Many times the system was sensitive to the length of the cables, the cables themselves seemed to break easily, and there was no good way to determine which cable of the two had failed. The cables were connected to a special card, called the drive controller.

13. The Drive Controller
Interface between the drive and the motherboard (system controller)
Obsolete as separate cards
Integrated with the motherboard and drives
Drive controllers are very important devices, as they are responsible for communications between the system and the drive. However, they are transparent these days. Virtually all PCs since the 486 have had the floppy controller circuits located on the motherboard.
At about the same time the major drive manufacturers started placing the drive controller on the back of the drive itself.

14. Legacy Drive Controller
Many years ago controllers were the big massive cards as shown. They weren’t very reliable, and hard drive required that two cables were attached to the controller. If either of the cables failed, and they failed a lot, you had to determine which cable was bad while trying not to break the other. This is a controller for two ESDI hard drives. Many such controllers also provided connections for a floppy drive.

15. IDE/EIDE Interface 40-pin data connector Configuration Jumpers
IDE was first developed as a proprietary format, but its features were so strong that it soon became the standard for PCs. This interface is used for several devices, including CD-ROMs, ZIP Drives, Tape backup units, Optical drives, PC Card adapters, and so on. IDE is an acronym for Intelligent Drive Electronics, and is also known as ATA, or AT-Attachment.
This photo shows the business end of a typical IDE hard drive. On the left is the data cable connector, in the middle is the jumper block, and on the right is the power connector. If you look at the data connector closely you will notice that it uses two methods to prevent cables from being attached backwards. The first method, shown by the lower yellow arrow, is a missing pin. Often this missing pin is met with a cable that has no hole at that location. If the cable is installed backwards it cannot be fully inserted.
The second method, shown by the top yellow arrow, is less obvious. The connector pins are surrounded by a shell that goes all the way around the pins. At the top there is a small section of this shell that is removed. Many IDE cables have a matching protrusion, again to prevent the cable from being installed incorrectly.
40-pin data connector
Configuration Jumpers

16. This photo shows the controller side of a current 4. 3 GB drive
This photo shows the controller side of a current 4.3 GB drive. This EIDE drive contains the entire controller circuit, which was formerly on the card shown earlier. Then the entire package simply has a common interface, the EIDE interface. This interface is also called ATA. Floppy drive interfaces have also become standardized. The floppy controller circuits are now usually in the same IC that controls the serial and parallel ports.
By putting the controller directly on the drive, the manufacturer is free to build the drive mechanics and controller circuitry in any manner. The motherboard manufacturers are free to build a simple interface that will communicate with any EIDE drive. As long as they both adhere to the EIDE standard everybody is happy.
EIDE Controller

17. SCSI Interface Configuration Jumpers? 50-pin data connector
Unless you look closely, the differences between a SCSI HDD interface and the EIDE interface are not obvious. First, the SCSI connector is 50 pins wide, not 40. Second, there are no master/slave jumpers. However, some SCSI drive will contain jumpers for the SCSI ID number. So be careful and look closely when you are working in an environment of mixed computers, such as PCs and Macs.
50-pin data connector

18. SCSI Host Adapter Internal External
SCSI drive don’t use controllers, instead they use a Host Adapter. This is what a typical SCSI Host Adapter card looks like. It has an 50-pin internal connector for ribbon cable to connect internal SCSI devices, such as hard drives or CD-ROMs. You can also see the external device connector, which is used for external drives and other devices such as scanners.

19. SATA Interface
The newest member of the group is the Serial ATA Interface. There’s no mistaking this one for anything else. Like SCSI, it has no configuration jumpers.

20. Hard Drive Installation and Setup

21. IDE Cables
IDE cables generally come in two flavors, multiple device cables and single-device cables. The difference is that a multiple-device cable has three connectors, and a single has just one connector at each end. There is a third flavor which isn’t used much, that being the cable-select variety. This type of cable operates in much the same fashion as the floppy drive cable, where the two hard drives are configured by the cable itself.
The important points are that the cable has 40 conductors, and the stripe almost always goes towards Pin 1. However, the cable can be connected backwards at each location and still work properly.

22. Motherboard Ports
All contemporary PCs have at least two IDE ports. These ports are referred to as the Primary port and the Secondary port. Generally you connect the boot drive to the primary port, although this isn’t always necessary.
These ports can be turned off and configured in the BIOS. When you have problems with a port, always verify that the port is enabled, and in most cases set to the Auto-detect mode. Many motherboards have a different style connector, one just like the drive connector shown earlier. These connectors make improper connection unlikely. You should always be careful that you connect IDE cables correctly.
The board shown is labeled, but you have to look closely to find the information you are looking for. The arrow points to the only clear indication as to which port is the primary and which is the secondary. The circles show the information that tells you which end is pin one, and where the stripe is supposed to be.

23. Master/Slave Settings
Each IDE port can support two devices. With minor exceptions, you can connect two hard drives, CD-ROMs, or other devices in any combination. In all cases one of the drives must be configured as a master, and one must be configured as the slave.
Lately most drive manufacturers provide the drive jumper settings on a label right on the drive as shown here. At least one manufacturer has decided that the labels will be upside-down, with respect to the way most hard drives are installed. Configuration information is available on the manufacturer’s websites, where they normally have info on every drive they ever built.

24. EIDE Enhanced IDE Larger Drive Capacity Faster Transfers
Two ports, and two devices on each port
ATAPI
EIDE, or Enhanced IDE, is an important improvement in the basic IDE system. The original IDE system did not allow for drives to be sized larger than 504 MB, a severe limitation these days. With EIDE, drives can be as large as 128GB.
EIDE incorporates faster data transfer modes, the main feature of the newer port specification. These faster modes allow data transfer rates several times what was previously available. With motherboard speeds now at or above 133MHz, this is an important feature. EIDE systems now have two ports, where IDE systems had one single port. This allows four devices in total to be attached to the computer. EIDE also provided the ability for the drive to tell the computer about itself.
ATAPI, or ATA Packet Interface is another use for the EIDE port. CD-ROM drives, for instance, all use the ATAPI interface.

25. Mounting Screws Control cable Power connector Mounting screws 25
A computer hard drive is a sealed device. If you open the drive case, that drive will probably never work again. Never break the seal when you work with the hard drive. The clearance between the head and the disk is much smaller than a dust particle. If even a tiny dust or smoke particle gets into the case, it can cause the drive to fail. Notice the four mounting screws. These are the only screws you should insert or remove from the drive. They are used to hold the drive in the chassis.
Power connector
Mounting screws 25

26. Safety First Turn off the power before you open the computer.
Wear an antistatic wrist band grounded to the computer when handling any computer component.
Be careful of the sharp wires on the component side of the disk drive.
Always remember—SAFETY FIRST. Turn the computer power OFF before opening it up.
Get in the habit of wearing your antistatic wristband and connecting it to the chassis of the equipment you are handling.
Also, circuit boards have sharp parts that may scratch or puncture your skin, or catch on your clothing. Be careful when working with circuit boards.

27. Physical Drive Logical Drive
It is important that you understand the difference between the physical hard drive and the logical hard drive. The physical drive is the one you can hold in your hand. The logical drive is the one you access through the software. A physical drive may contain several logical drives. Heath (C:) and Heathkit (D:) displayed on the right here, are both on the same physical hard drive.

28. Setup Standard Setup Standard Chipset Advanced P o w e r M g m t17
Setup
Standard
PCI/PnP
Chipset
Advanced
P e r i p h e r a l
P o w e r M g m t
Standard Setup
Pri Master
Pri Slave
Sec Master
Sec Slave
Floppy A
Floppy B 17
Date/Time
It is also important to keep track of any information about the drive. Keep any data sheets with the drive. SETUP may give you information about your drive. There may be several hard drives in the computer. At the setup level they are called Primary Master, Primary Slave, Secondary Master, and Secondary Slave. The Primary Master almost always contains drive C. If there are logical partitions, that drive may also contain other drives such as D and E. Write down the SETUP information before removing the drive. For IDE drives the display shown here is typical. The Type, LBA setting, Block Mode, 32-bit Mode, and PIO Mode settings are important. If this data is not correct, the files on the drive may not be accessible. LBA, Logical Block Access, must be enabled (turned on) for disk drives larger than 528 MB. If it accidentally gets turned off, writing to the disk may corrupt and destroy existing disk files. This is the drive configuration. When you install a new drive, SETUP must match the drive.

29. Master and Slave on same cable.
The Master and Slave drives share a single control cable. Thus, the Primary Slave is on the same ribbon control cable, as the Primary Master. Which one is the master and which one is the slave is determined by jumpers on the drive.

30. Mounting Screws Control cable Power Connector Mounting Screws
Write down the location and orientation of the control and power cables. It is often helpful to put masking tape on the cables with the orientation “TOP” or “BOTTOM” written on it. Although some cables are keyed to prevent incorrect connection, some are not. Many hard drives have pin 20 of the control cable connector cut off, to indicate cable orientation. Many control cables do NOT have a key plug in the corresponding connector. The drive will not work if the control cable is put on wrong!
Power Connector
Mounting Screws

31. Hard drive removal Open the cabinet. Disconnect cables.
Remove mounting screws.
Lift out the drive.
The physical removal of the hard drive is a simple four-step operation: open the cabinet, remove the mounting screws, disconnect the drive cables, and carefully lift out the hard drive.

32. Control cable Power Connector
Here is a typical example. Looking in from the top of the chassis, you can see the power and control cables connected to the hard drive.

33. Control Cable Power Connector
Gently disconnect the power cable. Then gently disconnect the control cable. Installing a new drive works with the same steps in reverse order.

34. FRAGILE Handle the hard drive with care.
DO NOT DROP OR
JAR
When a drive is out of a computer, treat it more carefully than you would a circuit card. In addition to being sensitive to static electricity and warping, the hard drive also contains disks, which are likely to be damaged if the drive is dropped or jarred. The newer IDE, EIDE and SCSI drives have some built in protection, but the older ESDI and ST-506 drives are very sensitive.

35. After you complete the mechanical part of installing a drive, you must run SETUP. First go to that section of SETUP for the hard drives. Here, you use the down arrow to highlight the drive you wish to configure. The Primary Master is highlighted on this screen.

36. Primary Slave Hard Disk
Type : Auto
LBA/Large Mode : Off
Block Mode : Off
32Bit Mode : Off
PIO Mode : Auto
For IDE or EIDE drives, the type is AUTO. In most cases, this is all you need to do. The drive communicates with the BIOS, and the BIOS is automatically adjusted to handle the new drive. After you have set this drive to Auto, you Save and Exit, using the F10 key as noted at the bottom.

37. SATA Serial AT Attachment (SATA) standard Data storage standard
Interface transparent to operating system
Supports previous parallel ATA standards
Burst rate 150 MB/sec
The Serial AT Attachment, or SATA, is the latest ANSI hard disk drive interface standard. The standard covers how data storage devices interface to the computer. SATA is a hardware standard. For that reason, the interface is transparent to the operating system. That is, the operating system communicates with a Serial ATA device just like it would with any parallel ATA storage device. At this time the SATA standard supports a maximum burst rate of 150 megabytes per second. Prior to the introduction of the 865 and 875 Intel chipsets the only way to interface with an SATA device was through a controller on an external PCI card. That imposed a bus-limited data transfer rate of 66 megabytes per second. Now that the SATA interface is part of the motherboard controller, the full 150-megabyte-per-second burst rate may be achieved.

38. SATA Interface Signal Contacts Signal Cable Connector Drive Socket
The SATA interface connectors are very different from the typical ATA connectors. There are two cables, the signal cable and the power supply cable. The signal cable uses a twisted pair of conductors for the transmit signal and a second twisted-pair for the receive signal. Each wire pair use low-voltage differential amplifiers for improved noise rejection and longer cable lengths. I’ll give you a detailed explanation of differential and single-ended signaling in a late presentation. All together there are seven contacts within the signal connector—two each for the receive and transmit differential signals and three for the various cable shield grounds. These are shown on the “drive socket assembly.”
Drive Socket
Assembly
Cable
Assemblies

39. SATA Interface Drive Socket Assembly Power Contacts Power Supply
The power supply cable has 15 connectors. There are three for 3.3-volt power, three for 5-volt power, and three for 12-volt power. Five of the remaining connectors supply ground. The 15th connector, pin 11, is reserved for future use, and grounded at this time.
You may be able to see in the socket assembly that the signal and power contacts are different lengths. These allow you to “hot-swap” a drive without causing irreparable damage. That is, they make it possible to remove a defective drive and install a replacement without switching-off power to the drive or the computer.
Power Supply
Cable Connector
Cable
Assemblies

40. SATA Interface Drive Socket Assembly Manufacturer Test Pins Cable
Finally, note that there are no jumper blocks to configure on an SATA drive. Those “manufacturer test pins” shown on the left side of the socket assembly, are simply that—a way to test a drive during manufacture. They are not used to program the operation of the drive, and you may not find them on every SATA drive.
Cable
Assemblies

41. SATA Hard Disk Drive Power Adapter Plug Test Pins Power Connector
Here is an example of an SATA drive with its cables connected. The power supply cable on this drive has an adapter that allows you to plug the drive into a common power supply drive connector. Did you notice that like every other ATA drive, this drive does not use 3.3-volt power? The SATA power connector was designed to accommodate 3.3-volt power, but it is not being used at this time.
The signal cable on an SATA drive is one of its best features. The cable a whole lot narrower than the usual 40- or 80-conductor ATA signal cable. That makes it much easier to route inside the computer case; and because it is so narrow, it allows better air circulation for improved cooling. Recall that in addition to being very wide, the ATA parallel cable is also very short—no more than 18 inches. The SATA cable, on the other hand, can be up to one meter in length. And finally, you don’t have to be concerned about properly connecting and programming an SATA drive. There are only two connectors on the signal cable, and they are identical. One plugs into the drive, the other into the motherboard host connector, and there are no configuration jumpers to ponder over.
Test Pins
Power
Connector
Signal
Connector

42. Hard Drive Partitions

43. File Allocation Table (FAT)
OS’s road map to the disk
How the OS keeps track of which clusters belong to which files
How the OS keeps track of bad sectors
Two copies maintained and kept up to date.
With all of the talk about sectors, tracks, clusters, cylinders and platters, an OS needs a clear road map to keep track of where all the files on a disk are located. This road map is called the File Allocation Table or simply FAT for short. It is a table created and maintained as data is written, deleted or moved around on a disk. This table tells the OS exactly where every file is located and it identifies any sectors which found to be bad. It is deemed so important that DOS/Windows keeps two identical versions of the FAT on all disks in case one is damaged or lost.

44. Formatting Low Level Formatting - Performed by the Drive Manufacturer.
High Level Formatting - Performed by the PC User via the FORMAT Command.
All hard disks must undergo two levels of formatting before they can be used. The manufacturer of the drive performs low-level formatting. The user of the PC can perform high-level formatting. It is routinely performed on floppy disks and sometimes must be performed on the hard drive as well. Let’s take a closer look at the differences between low level and high level formatting.

45. Low-Level Formatting Blank Disk Sectors and tracks defined
Low-level formatting changes the disk from one single large surface into the various tracks and sectors into which data can be written.
Blank Disk
Sectors and
tracks defined

46. Low Level Formatting Performed at the factory.
Converts the single blank surface into tracks and sectors.
Finds and remaps bad spots on the disk so that the operating system can avoid them.
Generally speaking, this requires special equipment and is done at the factory where the disk is manufactured. It breaks the single recording surface up into tracks and sectors. At the same time it detects and re-maps defective areas so that the operating system can avoid them. But this is only the first step in preparing the disk. Before it can be used, someone must also perform a high- level format.
Low-level formatting was a typical hard drive operation many years ago. When drives became faster, and the data storage areas became much smaller, a low-level format became impractical in the field. This happened about the time that IDE hard drives started appearing.

47. High Level Formatting
Originally performed by the vendor of the computer.
Creates boot record, FAT, and the root directory.
Performed with the FORMAT command.
If you have ever formatted a floppy disk, then you have performed a high-level format. While you will perform this operation routinely with floppies, formatting a hard drive is usually a much more serious undertaking.
Originally, the hard drive in your computer was high-level formatted by the computer manufacturer or vendor of your computer. This must be done prior to loading the operating system. High-level formatting creates the boot record, the FAT and the root directory. It is accomplished by a special command called FORMAT.

48. Partitioning Makes the hard disk compatible with the OS
Prepares hard disk for high-level format
Divides hard disk into partitions or makes it one large partition
Performed with the FDISK utility
Somewhere between low-level formatting and high-level formatting, the hard disk must be partitioned. Partitioning is a necessary step in preparing the disk for an operating system. In our case, the operating system is DOS or Windows, both of which provide a special utility called FDISK to handle partitioning. As the name implies, partitioning is a way of dividing up a hard disk into sections called partitions. In particular, it allows a single physical hard drive to be divided into two or more logical drives, each of which can behave as if it were a separate hard drive.

49. FAT and FAT 16 DOS, Win 95, Win 98 2 GB Maximum Partition
32 KB 2 GB
There are several types of partitions that can be applied to a hard drive. The first, and most widely used to date is the FAT or FAT 16 system. The two terms almost always refer to the same thing. FAT is the structure installed by default in all DOS and Windows 95 machines. On many computers with Windows 98 you will also see FAT 16.
The biggest problem with FAT 16 is that it can only support a 2GB hard drive volume, maximum. Since you can no longer buy a hard drive smaller than 2GB, manufacturers had to divide larger drives up into 2GB partitions. If your computer came with Windows 95 and a 5 GB hard drive, you were given three “logical” drives, C: D: and E:. C and D are 2 GB, and E was probably 1GB. Just a bit confusing, but it works.
Another drawback is that a 2GB drive has 32 KB clusters. That means that every file you store on the hard drive uses up space in 32 KB increments. If you save a 1 KB text file, 32 KB is used up on the hard drive to store the file. That’s not very efficient.

50. VFAT Win 95 and Win 98 2 GB Maximum Partition 32 K Cluster @ 2 GB
Long File Names
Windows 95 brought us an enhancement to the FAT 16 system. You probably recall that one of the best features of Windows 95 was its use of long file names. This feature was made possible by the use of the VFAT, or virtual FAT. VFAT is a scheme where Windows can handle long file names under the old FAT 16 system. VFAT doesn’t change the structure of the disk at all, it is really a software solution to a hardware problem.

51. FAT 32 Win 95 and Win 98 2 TB Maximum Partition 4 KB Cluster @ 2 GB
Late in the life of Windows 95, Microsoft came out with a utility that could transform your hard drive to a new partition structure. This structure lifted most of the limitations in the FAT 16 system. Most notably the 2 GB partition limit has been blown away, the new limit is 2 Terabytes.
At the same time cluster size was reduced dramatically. Where on our previously mentioned 5 GB drive each cluster would have eaten up 32 KB, on a FAT 32 drive each cluster uses up only 4 KB. Depending upon the type of data you are storing, converting to this system could save you a ton of disk space.
Most Windows 98 machines shipped today utilize the FAT 32 system. Older Windows 98 machines had a utility that would allow the system to be converted to FAT 32. Windows 95 can handle FAT 32, but you need the latest version and the conversion process is not automated.

52. Partition Format Load OS
This sequence is important. The partition process defines the disk’s geography. A hard disk must have a partition, or several, before it can be formatted. Formatting is done by an operating system tool. Normally you use the OS you plan to implement to format the drive. Formatting allows the drive to properly communicate with the OS. Once the drive is formatted you can store data on it. You don’t have to load the OS onto every drive, just those that will become a boot drive, or the main drive in the system.

53. Fixed Disk Setup Program (C)Copyright Microsoft Corp. 1983 - 1995
FDISK Options
Current fixed disk drive: 1
Choose one of the following:
1. Create DOS partition or Logical DOS Drive
2. Set active partition
3. Delete partition or Logical DOS Drive
4. Display partition information
5. Change current fixed disk drive
Enter choice: [5]
After you complete SETUP, you may want to run FDISK. Typically, here is what you do. This discussion assumes that you have added a second hard drive to your system, and that you are running FDISK from a file located on the primary hard drive. The first step is to change the current drive, to the drive you wish to work with. Enter choice five to switch to the second drive.

54. Fixed Disk Setup Program (C)Copyright Microsoft Corp. 1983 - 1995
FDISK Options
Current fixed disk drive: 2
Choose one of the following:
1. Create DOS partition or Logical DOS Drive
2. Set active partition
3. Delete partition or Logical DOS Drive
4. Display partition information
5. Change current fixed disk drive
Enter choice: [1]
Notice the “Current fixed disk drive: 2” statement.
Having changed to the second drive, you will need to access the first option: “Create DOS partition or Logical DOS Drive.”

55. Create DOS Partition or Logical DOS Drive Current fixed disk drive: 2
Choose one of the following:
1. Create Primary DOS Partition
2. Create Extended DOS Partition
3. Create Logical DOS Drive(s) in the
Extended DOS Partition
Enter choice: [2]
Press Esc to return to FDISK Options
There are three options here. Because this is the second drive, you will probably want number two: “Create Extended DOS partition.”

56. Create Extended DOS Partition
Current fixed disk drive: 2
Partition Status Type Volume Label Mbytes System Usage
E:1 A EXT DOS JSMITH FAT %
Extended DOS Partition already exists.
Press Esc to continue
The new partition you create can use any part or all of the new drive. We have made the entire drive into drive E:.

57. Display Partition Information
Current fixed disk drive: 2
Partition Status Type Volume Label Mbytes System Usage
E:1 A EXT DOS JSMITH FAT %
Total disk space is 1032 Mbytes (1 Mbyte = bytes)
The Extended DOS Partition contains Logical DOS Drives.
Do you want to display the logical drive information (Y/N)....?[Y]
Press Esc to return to FDISK Options
When you have set up your partitions, you will want to display that information to check your selections.

58. Display Logical DOS Drive Information
Drv Volume Label Mbytes System Usage
E: JSMITH FAT %
Total Ext DOS Partition size is 1032 Mbytes (1 MByte = bytes)
Press Esc to continue
The logical drive information confirms our selections. Once you start using the drive, it is hard to undo these settings. You will need to back up the data on the drive, use FDISK to change the partition, and then restore the data.

59. You must FORMAT ALL new Logical Drives.
Finally, after you install a new logical drive, you have to format that drive.

60. C? D? E? F? Master --Two Partitions Slave --Two Partitions
Let’s say your system contains two IDE hard drives, each divided into two separate partitions (logical drives). How are the drive letters assigned to these logical drives? Not like you might expect...

61. C: Master, Primary Partition E: Master, Extended Partition
Master --Two Partitions
Slave --Two Partitions
C: Master, Primary Partition
E: Master, Extended Partition
…the primary partitions always come before any extended partitions. And master drives take precedence over slaves. You can take this arrangement several steps further if you have more than just two partitions, but these rules still apply.
D: Slave, Primary Partition
F: Slave, Extended Partition

62. Maintaining a Hard Drive

63. Hard drive performance has been slowing down over time.
Symptom
Hard drive performance has been slowing down over time.
One of the most common is that its performance slows down over time. This happens when the information on the disk gets fragmented. Over time as files are recorded, moved, deleted, and modified, the files become fragmented. Instead of being recorded in one unbroken segment, they are recorded as many different fragments which are linked together. The disk can still read the information but it may take several head moves to read a single file. This slows the operation of the hard drive.
Fortunately, Windows provides you with a convenient way of defragmenting the hard drive. So if the hard drive appears sluggish try defragmenting it before taking more drastic measures.

64. PC will not boot from the hard drive.
Symptom
PC will not boot from the hard drive.
Here is a particularly frustrating problem. The system will no longer boot from the hard drive. And because the system will not boot, you can’t examine or change anything. How do you proceed when you have a problem like this? Let’s begin by thinking about some of the things that could cause this problem.

65. Possible Problems: The SETUP configuration has been changed or lost.
One or more of the MS-DOS files on the hard drive may be corrupt or missing.
The partition table or boot sector may be corrupt.
The hard drive may have a mechanical or an electronic malfunction.
First the SETUP configuration may have been changed or lost. Fortunately, you can examine SETUP even if the machine will not boot from the hard drive. So you should go into SETUP and verify that the configuration is correct. If it is not, you need to find out why. Did someone inadvertently change it? Was the configuration lost because the CMOS backup battery is dead?
A second possibility is that one or more of the key startup files is missing or has been corrupted. You cannot boot from a disk unless it contains these files. Recall that it is a good idea to keep an emergency boot floppy disk that contains these files for just such a situation. In order to get to a command prompt, boot the computer from the emergency boot disk or from any bootable floppy disk. Once you get a prompt, you now have a shot at determining the state of the hard drive.
There are several utilities available that will allow you to test and in some cases fix a hard drive. You would load a diagnostic program and attempt to access the hard drive. If you can access the drive, it is probably working even though the boot files are corrupted. If so, the corrupted files can be replaced.
If the partition table or the boot segment has been corrupted, the diagnostic program may even be able to fix that also.
A fourth possibility is that the hard drive has a mechanical or electronic malfunction. If so, it may not be economically feasible to repair it. Of course, you can simply replace the hard drive. The question is: Can you save the data that is on that drive? If you have made regular back-ups, this will not be a problem. If you did not make frequent back-ups, key data may be lost forever. The only real insurance against data lost is to back-up frequently.

66. “How good are your backups?”
You can reload Windows
You can reload applications
You can reconfigure the GUI
Can you recreate your data?
Ultimately your troubleshooting success depends upon how well you are prepared. Do you have the tools you’ll need? Do you know how to use them? And, do you have a backup in case the error is unrecoverable?
In the PC support industry, time is everything. You can reload an entire computer without too much trouble from the CDs, but it takes time. On the other hand, the creative or analytical work of a business is often not possible to recreate. Some of that data may have taken years to build, and may represent the value of the business itself. What’s that backup worth now?

67. Backing up a PC can be a complex job, which is probably why there are so few backups being made. But once you have a handle on the concepts, it’s actually simple and boring.
This slide shows the Windows 2000 Backup program. It’s not too hard to follow, and the Help files make it even easier. The backup program you ultimately use might be different, but the main concepts are the same regardless which program you use.

68. The Backup program in Windows 2000 is more powerful than any previous Microsoft backup tool. It’s just as complicated, but there are some Wizards that take us through the basic tasks. Let’s take a look at making a backup of the important system files in Windows 2000.

69. The previous slide showed you the complex side of Windows 2000 backup
The previous slide showed you the complex side of Windows 2000 backup. Before you get to the complicated interface there are three Wizards that help you perform the most common tasks. Let’s use the Wizard to back up the most important system data.

70. Not much going on here, just click Next…

71. The default is to back up everything on the computer, but there’s really no reason to do that now. Let’s back up the System State data.

72. After you decide “what’ to backup, you have to decide “where” to put the backup. In most cases we’re talking about a tape drive or some other network drive that is backed up automatically. For now, let’s put the backup on the hard drive somewhere. Then later we can put it on a CD or somewhere just as safe.

73. One of the nicer features of Windows 2000’s wizards is a summary screen. All the choices that you selected are shown one last time before the backup actually begins. If you want to change settings you can use the Back button.

74. Once you click OK, the actual backup starts
Once you click OK, the actual backup starts. The amount of time this requires depends upon how many files you are saving. This one took about a minute.

75. Finally, the backup is complete. Let’s take a look at the report.

76. This report is a record of how much data was backed up, when it was done, and the elapsed time. You probably don’t need this log for a backup of your home computer, but a large company might require that these logs be kept in a safe place.

77. The Backup Timeline Restore from Backup OS Loaded Apps Loaded Minor
Changes
Backup
CRASH!
Let’s look at a timeline of the events leading up to a typical restore scenario. You install the operating system on the first day, and the applications a couple days later. Everything is working fine on the fifth day, so you make a backup of the system files. Over the next week or so you make minor changes to the system, things like shortcuts and you load some small utility software. On the 20th day, the system crashes.
But that’s OK, because you made a backup. You restore from the backup and everything is back to normal, right?
Day 1
Day 3
Day 5
Days 7-15
Day 20
Day 21

78. The Backup Timeline Changes are lost! Restore from Day 5 Backup OS
Loaded
Apps
Loaded
Minor
Changes
Backup
CRASH!
Almost back to normal. The backup was created on Day 5, but that backup didn’t include the minor changes made during Days What does this mean to the system you have just restored?
Day 1
Day 3
Day 5
Days 7-15
Day 20
Day 21
Changes are lost!

79. Create Regular Backups
Changes made between the Backup and the Restoration are lost.
What it means is that any changes you made between the day you made the backup and the day you restored the crashed system are lost forever.
In our example that doesn’t amount to much. But imagine you are building a website for a big customer, your backup was made three months ago, and the new websites aren’t backed up…what does that crash mean to you then?

80. Optical Drives

81. The CD-ROM Storage 650 MB X1 = 150 KBps = 450 Floppy Disks
CD-ROMs are convenient devices for permanent storage of programs and data. What ROM chips are to memory, the CD-ROMs are to disk storage. CD-ROMs are the most common media for distribution of software. It is almost unthinkable to have a desktop computer without a CD-ROM drive. The CD-ROM can hold up to about 650 megabytes of data. The capacity is equal to about 450 floppy disks.
X1 = 150 KBps

82. Floppy Disk CD-ROM Magnetic Laser Reading Tracks are concentric
One spiral track
CD-ROMs are obviously different from floppy disks. Let’s take a moment to compare them. First, a floppy disk is recorded and read by magnetism, while a laser light beam reads a CD-ROM.

83. Tracks are separate circles Track 0 at the outer edge CD-ROM
Floppy Disk
Magnetic
Tracks are separate circles
Track 0 at the outer edge
CD-ROM
Laser Reading
One Spiral Track
From Inside to Outside
End
Track 0
Track 79
Second, magnetic disks have tracks that are concentric circles. CD-ROMs have a single “track” that spirals from beginning to end.
Magnetic disks have track zero at the outside, and the highest numbered track is on the inside. CD-ROMS start recording on the inside and spiral toward the outside.
Beginning

84. 16,000 laps per inch 135 tracks per inch
The spiral here is opened up so that you can see it. On an actual CD, the spacing is such that there are 16,000 laps per inch. Compare this to a high-density three-and-a-half-inch disk, which has 135 tracks per inch.
135 tracks
per inch

85. Angular rate is constant Shorter track on inside
Magnetic Disk
Angular rate is constant
Shorter track on inside
means tighter packed data
CD-ROM Disk
Linear rate is constant
Shorter track on inside
means higher rotational
speed there.
Another difference between CD-ROM drives and magnetic disk drives is rotation speed. For floppy disks and hard disks, the rotation speed is constant. Data on the inside track is more tightly packed than data on the outside track. On CD-ROM disks, the speed must change so that data on the inside is packed at the same density as data on the outside. This conforms with music CDs that must pull music off at a constant rate to achieve high fidelity reproduction.

86. Track 0
You might have heard that CD-ROMs have up to ninety-nine tracks. As you have just seen, there is only one physical track that spirals from the center out. For the sake of logic and to use similar terminology, the several files on the CD-ROM are referred to as tracks. Each track corresponds to a different file. As shown here, a track may be longer than one lap around the disk, like track zero, which takes two laps. Or, it may be less than one lap, like track one, which is only three fourths of a lap.
Track 1

87. Sector In addition to data, each sector also contains
Error Detection Codes (EDC) and Error Correcting Codes (ECC).
Tracks are further divided into sectors. All sectors have the same number of bytes. In addition to the computer data stored in the sector, there are also error detection codes and error correcting codes. In most cases these allow the computer to correct data read from the CD-ROM, but even if the data cannot be corrected, the fact that there is an error can be detected.

88. OK Never wipe in line with the Sector!
If you desire to clean the disk, always wipe from the center out, so that you are cleaning across the sector. If you were to make a scratch in line with the sector, you could destroy the error detection and correcting codes and not only lose the data but the ability to detect and/or correct it.

89. Clear Protective Coating
Top or Label Side
Reflective
Metal
Layer
Let’s take a moment to look at how a CD is constructed. The CD is like a sandwich. On top is a thin layer that can include the label. In the middle is a layer of reflective metal, like the silver coating on a mirror. The metal in the CD is usually aluminum. On the bottom is a clear coating to protect the metal layer.
Clear Protective Coating

90. Data, in the form of PITS and LANDS
Beam is reflected
Beam is absorbed
The metal layer is organized into a single spiral track as you learned before. The data is stored on this track in the form of non-reflective pits and highly reflective lands. Although the clear coating protects the metallic surface, a scratch in the coating can obscure the data. Also, because the coating on the label side is so thin, a scratch on that side can damage the pits and lands. You must protect both sides of the CD from scratches.

91. Recordable Media Gold Layer
In a CD-R, that’s a recordable CD, the metallic layer is sometimes gold.

92. Recordable Media Photo-sensitive Dye Layer
A photosensitive dye layer covers the gold. This dye can be one of several colors, usually blue or green. The CD-R drive has a more powerful laser than a read-only drive. In the write mode, the laser causes a change in the green dye layer so that the gold layer is obscured or revealed. Afterwards, the disk works like a standard CD‑ROM disk. In the read mode, the laser power is reduced allowing the drive to read either standard CDs or Recordable CDs.
There are also CDs made today that use a photo sensitive layer that can be set either clear or opaque, like photo-sensitive sun glasses, or liquid crystal displays. These CDs, referred to as CD-RW, can be rewritten and changed.
CD-R is Write Once Read Many (WORM)
RD-RW is Read/Write, or Re-writeable

93. Connections and Specifications

94. Four Basic CD-ROM Interfaces
SCSI (Small Computer Systems Interface)
EIDE (Extended Integrated Drive Electronics)
Proprietary Bus
Other Interfaces
CD-ROM drives are not all the same. One of the biggest differences is in how they connect to the system. There are four basic CD-ROM interfaces:
•SCSI which is Small Computer Systems Interface
•IDE (Integrated Drive Electronics)
•Proprietary bus connection (the manufacturer’s own design)
•Other interfaces

95. Access Speeds Single-speed (1x) 150 KB/s Quad-speed (4x) 600 KB/s
Eight-speed (8x) MB/s
Ten-speed (10x) MB/s
Sixteen-speed (16x) MB/s
Twenty-speed (20x) MB/s
Twenty Four-speed (24x) 3.6 MB/s
Fifty-speed (50x) MB/s
The access speed of a CD-ROM drive is based on a unit of 150 kilobytes.Today it is hard to find a drive with an access time less than 600 kilobytes per second. If you are buying a drive to install in your computer, you probably won’t consider one that is less than twenty-speed. In mid-1996 ten-speed drives were rare. By late 1997 twenty-speed drives were common. Today fifty-speed and higher drives are available. But the true transfer rate depends more on how the drive is connected to the system than on the rated speed of the drive.

96. Installing and Maintaining a CD-ROM

97. Installing a CD-ROM Drive
1. Install or select the hardware interface.
2. Install the physical drive.
3. Install the device driver.
4. Link the device driver name to the operating system
Now that you understand the CD-ROM and the hardware required to connect the drive to the computer, you can think about installing a CD-ROM drive. This is a four step process. One, install or select the hardware interface. Two, install the physical drive. Three, install the device driver. And, four, link the device driver name to the operating system.

98. Primary EIDE Channel Secondary EIDE Channel
There are two primary ways that you will be installing a CD-ROM into a computer. You will either use existing connectors, on the motherboard or on an existing plug-in card, or you will add a new controller card for the CD-ROM. If you are using IDE or EIDE, the connectors may be on the motherboard or on an existing controller card. Remember there are separate connectors for the primary and secondary pairs of IDE devices.

99. CD-ROM Drive Locations
Regardless of the interface you are using, you will need to locate your CD-ROM so it is accessible. Remember that you will be inserting various disks in the drive from time to time. If the drive is going into the main computer chassis, you will need a 5¼-inch front opening.

100. Metal knockout Plastic snap out
When you remove the plastic panel from the front, you will probably find a metal panel that also needs to be removed.
Plastic snap out

101. Power to
CD-ROM Drive
With either a proprietary card or an existing EIDE connector, you will have to connect the CD-ROM drive to the computer’s power supply.
101

102. Control to CD-ROM Drive 102
You will also have to connect a control cable. The control cable will most likely be a ribbon cable. It may be a cable that is also connected to another device, such as the hard drive.
102

103. Connect the CD-ROM drive to the sound card
Finally, be sure you connect the audio cable between the CD-ROM and the sound card. Remember that the sound card uses this cable when you play an audio CD in your CD-ROM drive.

104. After the hardware is connected, you will have to make sure the software is set up to talk to your CD-ROM. If the CD-ROM is an IDE device, this will first mean running SETUP in the computer’s firmware. In setup, select standard and identify the proper IDE device as CD-ROM. Normally this will be either the Primary Slave or the Secondary Master.