A+ Operating Systems Technologies (220-232) ExamCram

A+ Certification, awarded by CompTIA® organization is the most widely recognized certification in the area of PC hardware and software technologies. To attain A+ certification, one need to pass 2 exams, namely, A+ Core Hardware Technologies, and A+ Operating Systems Technologies. These exams basically test the skills in assembling a computer, troubleshooting, and the ability to work with various operating systems. Linux is not included in the A+ Certification Operating Systems exam, as it has an exam of its own (Linux+ Certification), offered by CompTIA. The exam cram offers several final preparation points for candidates intending to appear for the A+ test. Latest objectives are available from Comptia.com website.

1. IDE hard disks:

- An IDE hard disk can have one Primary partition and one Extended partition. An Extended partition can be divided into one or more logical partitions. After partitioning the hard disk, each partition needs to be formatted.

- The File System Boot Sector is the first physical sector on any logical volume.

- The first physical sector on any bootable hard disk contains Master Boot Record, MBR.

- The command FDISK will destroy all the data on a partition or drive on to which it is run.

- The primary partition can be made bootable, by marking partition as active.

2. FAT:

- Windows 98 and Windows 95 OEM Release 2 support FAT32. Note that Windows NT does not support FAT32. NT supports only FAT16 and NTFS. Windows 2000 supports FAT16, FAT32, and NTFS.

- DOS standard FAT16 support drives up to 2 GB. FAT32 supports drives up to 2TB (Terabytes).

3. PC Utilities: The following DOS utilities are useful in proper maintenance of PCs.

A. SCANDISK: ScanDisk is a utility program that was added to DOS Version 6.0. SCANDISK is a better compared to CHKDSK. SCANDISK can fix errors on data storage devices such as hard disks, floppy disks, RAM drives etc, and DoubleSpace compressed drives. It analyzes and repairs damage to the following:

1. Physical clusters

2. File allocation table (FAT)

3. Lost clusters

4. Cross-linked files

5. Directory tree

6. MS-DOS Boot sector

7. DBLSPACE volume header, file structure, compression structure.

B. CHKDSK (Check Disk): CHKDSK command, one of DOS commands, examines your hard drive for error conditions and reports the total size of the disk, how many files are stored there, and the space remaining. CHKDSK also reports the total amount of conventional memory in your system and the amount of conventional memory available. Note that CHKDSK can't report extended memory.

C. DFRAG: The DFRAG.EXE is included with DOS6.0 and later. DEFRAG utility arranges the clusters of data on the hard drive to achieve better performance by placing all of the clusters for a given file together in a contiguous order. DEFRAG does not do any repair on your disk, and errors, if any will remain on the disk.

D. BACKUP: DOS has a backup utility since version 2.0.

4. .COM, .EXE, .BAT files are executable files.

5. DOS Boot up:

- IMPORTANT DOS FILES USED DURING BOOT UP ARE:

A. AUTOEXEC.BAT

- It does: Modifies the PC environment (PATH, SET, and other commands)

- Default Attributes: Nil

- Is it required for OS Start up: NO

B. CONFIG.SYS

1. It does: Loads low level device drivers and does performance tuning

2. Default Attributes: Nil

3. Is it required for OS Start up: NO

C. IO.SYS

1. It does: Loads basics Input/ Output routines for the processor

2. Default Attributes: Hidden / System/ Read Only

3. Is it required for OS Start up: YES

D. MSDOS.SYS

1. It does: Defines System File locations

2. Default Attributes: Hidden / System/ Read Only

3. Is it required for OS Start up: YES

E. COMMAND.COM

1. It does: The file contains internal command set and error messages

2. Default Attributes: Nil

3. Is it required for OS Start up: YES

4. Responsible for displaying the command prompt in a DOS based computer.

F. HIMEM.SYS

1. HIMEM.SYS must be loaded before EMM386.EXE

2. HIMEM.SYS is used to address the extended memory

G. EMM386.EXE

1. EMM386.EXE allows access to Upper Memory Area. Please note that the conventional memory of 1 MB is divided into 1. Lower Memory Area 640 KB, and 2. Upper Memory Area 384KB (1024KB-640KB).

H. ANSI.SYS



- The files AUTOEXEC.BAT, CONFIG.SYS, ANSI.SYS are not required for OS start-up. However, the files IO.SYS, MSDOS.SYS, COMMAND.COM are required for OS start-up.

- To bypass the CONFIG.SYS, and AUTOEXEC.BAT files during boot process of DOS, you need to press F5. F8 allows you to selectively bypass commands in AUTOEXEC.BAT, and CONFIG.SYS.

6. DOS allows you to set the following attributes using ATTRB command:

1. System

2. Hidden

3. Read-only

4. Archive



'+' sets and attribute

'-' clears an attribute

Examples:

- The command ATTRIB +H myfile.txt will make the file myfile.txt hidden. The other attributes that can be set using ATTRIB command are System, Read Only, and Archive.

- The command ATTRIB C:\private.txt +h +r will mark the file private.txt as both hidden and read only.

7. DOS, Windows3.1 Windows 95/ 98 operating systems have the following characteristics:

1. Each can have only one primary partition per hard disk

2. The primary partition is automatically assigned a drive letter

3. Each hard disk can have only one Extended partition

4. You can create one or more logical drives in the Extended partition.

5. The drive letters are assigned manually to logical drives.

8. The standard DOS partition cluster sizes are as given below:

16MB-127MB: 2KB cluster size

128MB-255MB: 4KB cluster size

256MB-511MB: 8KB cluster size

512MB-1023MB: 16KB cluster size

1024MB-2048MB: 32KB cluster size

Note that due to DOS limitation, the FAT on each hard drive partition can have 64K (65535) individual addresses. Therefore, it is clear, depending on the size of partition, this number dictates the size of each cluster. We arrive at 32KB cluster size by dividing 2048(MB) with 64(KB).

9. The Windows 95/98 system files include the following:

A. IO.SYS

B. MSDOS.SYS

C. WIN.INI

D. COMMAND.COM

E. SYSTEM.INI

F. SYSTEM.DAT

G. USER.DAT



- MSDOS.SYS, WIN.INI, SYSTEM.INI are text files.

- SYSTEM.DAT, USER.DAT files are part of windows Registry and can be edited using REGEDIT or REGDT32 utility. Registry files can't be read with standard text editors.

- Further, USER.DAT file corresponds to HKEY_LOCAL_USER and SYSTEM.DAT corresponds to HKEY_LOCAL)MACHINE.

10. HKEY_LOCAL_MACHINE is the hive where the information specific to the machine will be stored. The information may include, network settings, hardware drivers etc.

HKEY_LOCAL_USER hive stores data specific to user configuration, such as desktop color schemes, screen savers, wall paper, and user specific application settings.