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Hal.dll (location - systemroot\System32 - Windows NT-based operating system system startup file #7)
The hardware abstraction layer (HAL) dynamic library file. The HAL is a loadable kernel-mode module (Hal.dll) that interfaces Ntoskrnl.exe and drivers to abstract low-level hardware details (provides low-level interface to the hardware platform) from the operating system and provides a common programming interface to devices of the same type (such as video adapters). The Windows NT family operating system’s CD-ROM contains several Hal files and is one of the crucial elements to Windows portability across a variety of hardware platforms; this is down to the HAL. Setup copies the Hal file that is most applicable to the hardware configuration of the computer it will be installed and then renames it as Hal.dll. The HAL hides hardware-dependent details such as I/O interfaces, interrupt controllers, and multi-processor communication mechanisms – any function that are architecture-specific and machine-dependent. Processor execution is protected mode with paging. In other words, HAL is a layer of code that isolates the kernel, device drivers, and the remaining parts of the Windows executive from platform-specific hardware differences, e.g., motherboards. Entries in Boot.ini can include optional arguments that Ntldr and other components involved in the boot process interpret. An example of a hal.dll problem and its solution is explained below. Example: Ntldr loads the appropriate kernel and HAL images (Ntoskrnl.exe and Hal.dll) and if either of these important system files fails to load, Ntldr prints the message “Windows could not start because the following file was missing or corrupt”, followed by the name of the file. Ntldr reads the SYSTEM registry hive, \Windows\System32\Config\System, so that it can determine which device drivers need to be loaded to accomplish the boot, scans the in-memory SYSTEM registry hive and locates all the boot device drivers that are necessary to boot the system, adds the filesystem driver that is responsible for implementing the code for the type of partition (FAT, FAT32, or NTFS) on which the installation directory resides, aforementioned, to the list of boot drivers to load, loads these boot drivers, which should only be drivers like the filesystem driver for the boot volume and so forth. While this is occurring Ntldr updates the progress bar as each driver is loaded (not initialised at this time). The final stage that Ntldr takes part in is to prepare the CPU registers for the execution of Ntoskrnl.exe and calls on Ntsokrnl.exe to perform the remaining system initialisation. As is evident, Ntldr is a very important system file. The solution to “Windows could not start because the following file was missing or corrupt”, followed by the name of the file, is to read the detailed description pertaining to the RC herein. In addition to rebuilding the boot list, bootcfg will repair most “Invalid boot.ini”, “Windows could not start because of a computer disk hardware configuration problem”, “Could not read from selected boot disk”, “Windows could not start because the following file was missing or corrupt: Windows\System32\Hal.dll or …Windows\System32\xxxx.xxx”, “Check boot path and disk hardware”, “…\WINDOWS\SYSTEM32\CONFIG\SYSTEM”,or “NTLDR is Missing”. The command process may apply to other types of Hive/system files/.exe/.dll related Stop Errors, Blue Screens, Stop Messages, Exception Errors, or Fatal System Errors. Again from the RC, and with respect to any system file, using Hal.dll as the example, expand the file from the Windows CD-ROM, if necessary. The command would be expand d:\i386\hal.dl_ c:\windows\system32\hal.dll. Substitute d for the drive letter of the optical device. Now use the command RC command “copy”, as follows (where d represents the location of your optical device). First option: C:\>COPY(space)C:\Windows\ServicePackFiles\System32\HAL.DLL(space)C:\Windows\System32\hal.dll Second option: C:\>COPY(space)d:\i386\hal.dl_(space)C:\Windows\System32\hal.dll If the file to copy over means that an overwrite message appears, accept by depressing the “y” key. If the file to copy over is missing the file will just be copied. Once the file has been expanded, if applicable, exit the RC and restart the computer. Where the above procedure fails to fix the problem, follow the procedure below: There are eight commands that need to be entered in sequence to repair any of the issues mentioned previously. These commands are as follows: CD.. (takes the command prompt one level up) ATTRIB –H C:\boot.ini ATTRIB –S C:\boot.ini ATRIB –R C:\boot.ini del boot.ini BOOTCFG /Rebuild CHKDSK /R /F FIXBOOT At the C:\> prompt, modify the attributes of the Boot.ini file using the following commands. This ensures that the Boot.ini file is no longer hidden, removes the flag that sets it as an undeletable system file, and removes the flag that sets it as a Read-only file and cannot be amended to. ATTRIB –H C:\ boot.ini ATTRIB –R C:\ boot.ini ATTRIB –S C:\boot.ini At the C:\> prompt delete the Boot.ini file using the following command: del boot.ini By booting into the RC and executing the bootcfg /rebuild command (Windows XP Recovery Console command), used to manipulate the Boot.ini file or add if one does not exist, it will invoke the RC to scan each volume looking for the WindowsNT/2000 and XP installation(s) when run from a Windows XP CD-ROM (clicking on Recovery Console), or installed locally from a Windows XP CD-ROM (selecting the command from the Boot menu) only. When the RC finds a Windows installation, it will ask the user whether it should add it to the Boot.ini file as a boot option and what name it should display for the installation in the boot menu. The one caveat being that due to file compatibility problems with an original Windows Setup CD-ROM it will not be possible to proceed further. For example, if the original or Windows Setup CD-ROM XP SP1 is use to carry out the repair, you will get a message that the upgrade is newer than the version to be extracted from the CD. To overcome this problem, the solution is the use a “slipstreamed” setup CD, which adds the newer files to the original Windows Setup CD. The slipstreamed (a constantly up-to-date) Windows Setup CD will simply fix all future installations and CD-based repairs. The command bootcfg/ list and then ENTER with present the contents of the Boot.ini file. It is possible to use the command line utility, Bootcfg.exe. Boot into the RC and executing the bootcfg /rebuild command as before, it will invoke the RC to scan each volume looking for the WindowsNT/2000 and XP installation(s). When the RC finds a Windows installation, it will ask the user whether it should add it to the Boot.ini file as a boot option and what name it should display for the installation in the Boot menu. Use a “slipstreamed” setup CD. You will be prompted with a message (the exact verbiage will depend on your setup) that states that the Total Identified Windows Installs: 1; [1] C:\Windows. Assuming that the information is correct, enter “y for Yes”. You may have to enter the Administrator account password; if the Administrator account password does not have one, press ENTER and Bootcfg will begin the process of rebuilding the boot list to include the indicated Windows installation. You will be asked, “Enter Load Identifier”. This is the name of the operating system that will appear in the Boot menus. For consistency with the standard nomenclature used by Microsoft, enter “Windows XP Professional” or “Windows XP Home”. Enter Operating System Load Options: (that is: /fastdetect, is a must; for Intel’s XD or AMD’s NX CPU buffer overflow protection, and for only these CPUs, also include /noexecute=option. See the screenshot above). "Windows XP Professional" /fastdetect or “Windows XP Home" /fastdetect "Windows XP Professional" /fastdetect /noexecute=option” or “Windows XP Home" /fastdetect /noexecute=option” Although not essential it may be prudent to include the following command: CHKDSK /R /F Where boot sectors of important filesystem’s critical structures that a computer uses to start up are located and may be suspected of being damaged, run the command fixboot (without any parameters). Executing the fixboot, command simplifies the boot process on multi-booting machines, removing non-essential boot variables, which in turn will help ensure that the repair of the operating system installation will have the best opportunity of carrying out a successful boot into Windows. Hit “y” to “Sure you want to write a new boot sector to the partition C:?”, then ENTER. Exit and leave the RC. See: Windows Kernel (Lower Windows Executive).

Head
The mechanism that reads data from, and writes data to, a hard disk drive. Hard disk drives use one head for each side of each platter. The heads are attached to a common head-movement area so all heads move in unison. The heads are always positioned over the same logical track on each side of each platter. See: Data Loss & Data Recovery.

Hexadecimal Number Base System (HEX)
A big problem with the binary system is verbosity. When dealing with large values, binary numbers quickly become too unwieldy. The hexadecimal (base 16: includes only digits 0 through to 9 and the letters, A, B, C, D, E, and F) numbering base system solves these problems - they represent the values 0 through to 5 in decimal, and occupy a nibble. Hexadecimal numbers offer two features: hex numbers are very compact and easy to convert from hex to binary and vice versa because the hexadecimal number base system is based on the binary number base (base 2) system using a Nibble or 4-bit boundary. A hexadecimal value will begin with ‘0x’ or end in ‘h’. This indicated that the value proceeding ‘0x’ or preceding ‘h’ is in hexadecimal notation. The (x86) computer likes to "think" in 'groups' of eight (8) (hexadecimal number base system) digits instead of ten (decimal number base system). The byte is therefore a very important unit of measurement within the computing fraternity. The fact that computers use alternate number systems explains why 1K (1000) in Computerese is 1,024 and 4K (4000) is 4,096. Computers do not work with even powers of ten, but powers of two. See: Bit Binary Digit, Binary Number Base System, Byte, and Hexadecimal Number Base System (HEX).

High Density (HD)
A measure of the storage capacity of a floppy diskette or hard disk drive. For example, 15 or 18 sectors per track are recorded using MFM encoding. See: MFM Encoding (Modified Frequency Modulation Encoding).