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study guides and tutorials. MS DOS Boot Sequence and basic commands |
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POST - Power On Self Test - CPU performs a diagnostic on itself - CPU signals and initializes the system bus - A diagnostic check is performed on RAM - Installed plug and play devices are identified -The keyboard is checked - Examines the results of system checks and compares them to records stored in CMOS - Availble drives are queried - The operating system is loaded. Boot Sector - also know as sector zero or boot record. The record is 512 bytes and initiates the loading of two hidden files, IO.SYS and MSDOS.SYS The BIOS passes control to the boot record to start loading the OS after the boot record is loaded into RAM. IO.SYS After the boot record is read, IO.SYS is loaded into RAM. MSDOS.SYS SYSINIT next loads MSDOS.SYS into RAM - Communicates with BIOS to manage files, execute programs, respond to IRQs CONFIG.SYS Configures hardware devices, contains system settings such as device drivers, memory allocation and configuration, file system configuration. COMMAND.COM After the CONFIG.SYS has been read, then COMMAND.COM is read. - Loads an extention of the I/O functions -Internal command are loaded into RAM - Searches the root for AUTOEXEC.BAT and executes it COMMAND.COM - Acts as a "translator" for processing requests before they are sent directly to the processor. AUTOEXEC.BAT - Last component of the boot sequence - - Defines the software environment, loads execuatable device drivers, configures search paths, configures system variables. The only files absolutely required to boot a computer into DOS are IO.SYS, MSDOS.SYS, and COMMAND.COM Beginning with DOS 5, the boot process can be interupted by pressing the F5 function key. ****************** DOS commands - An internal command's code is part of the MS-DOS command interpreter, or command.comHard Disk Set Up - Partioning - used by an operating system to define a hard disk as a logical, separate unit. - MS-DOS can divide a hard disk into a primary partition (drive letter c:) and an extended partition. FDISK - FORMAT - ****************** DOS commands - An internal command's code is part of the MS-DOS command interpreter, or command.com FILES= specifies the number of files that can be open at one time BUFFERS= allocates space in memory to be used for file and data transfer. DEVICE= command in CONFIG.SYS loads device drivers into the memory. LASTDRIVE= command in CONFIG.SYS configures DOS to hold places in memory for drives. INTERNAL dos commands are in COMMAND.COM MS-DOS filenames must have 1 to 8 characters. There can be no spaces or punctuation in the filename. The file extension can have up to 3 characters, allowing 11 total characters in the filename.
DOS system files must reside in the primary active partition for the computer to start DOS. ........................ MSDOS.SYS - Only used by MS-DOS, not Windows 95. MS-DOS uses the fat16 file system. SHARE.EXE -
allows file locking in MS-DOS. MSD - MS-DOS utility that allows you to view the system's processor type. DIR and CHKDSK both can give the total disk space on an MS-DOS system. The ROM BIOS is programming that communicates directly to a computer's hardware. As programs read and write to the disk, fragmentation occurs. It takes longer for the computer to access fragmented files because these files are stored in noncontiguous sectors on the disk. Disk defragmentation will make file clusters contiguous, and speed up the hard drive data transfers. Typical commands found in CONFIG.SYS are break, buffers, device To delete a corrupted IO.SYS file you need to remove the proper attributes first. attrib -r-s-h command removes the (-r) read only (-s) system (-h) hidden tags on the IO.SYS file. In DOS use the F3 key to repeat a command.
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Hardware
Topics: Basic PC Overview
Operating
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