Реферат: DOS And Unix Essay Research Paper Compare

Releases such as 1.1, in which the number to the left of the decimal point is

the same as the previous version depict relatively minor changes from the

previous release. By contrast, Version 2.0 was largely a new system. In March

1983, IBM introduced the PC/XT, its first personal computer with a hard disk. It

came with a new variant of MS-DOS, Version 2.0. In this version, Microsoft

incorporated many ideas from the UNIX system for which it was also a vendor. For

example, incorporating minor changes, the MS-DOS file system was taken largely

from UNIX. In addition, the shell was improved, and Version 2.0 supported a new

floppy diskette format, the 360K as well as user installable device drivers,

print spooling, system configuration and memory management. At this point,

MS-DOS was established as the dominant operating system in PC market. In August

1984, IBM released its first 286 chip based PC, the PC/AT. The PC/AT supported

memory up to 16 Mb and had the ability to run multiple programs at once.

However, the version of MS-DOS that shipped with the PC/AT was 3.0, which

supported neither of these. Rather, it ran the PC/AT in a mode that simulated

the 8088, only faster. Since the PC/AT came with a 1.2Mb disk drive, battery

backup clock, and configuration information in the CMOS, support for these

devices was added. What’s more, hard disks larger that 10Mb were now supported.

In addition, the command processor (shell) was removed from the operating system

and made into a separate program. In November 1984, 3.0 was replace by 3.1 which

provided the first support for networking. In 1987, IBM came out with the PS/2

line of PC which shipped with MS-DOS 3.3, providing support for both 720K and

1.44Mb 31/3 floppy disk drives. With Version 4.0, Microsoft added the DOS shell,

a menu driven shell rather than the previous keyboard driven ones. In addition,

it now provided support for hard drives larger than 32 Mb. A major new release,

MS-DOS Version 5.0 was shipped in April 1991. Although this was the first

version that made any serious use of the extended memory, it still had the

restrictions that programs could not exceed 640K. However, it had the ability to

locate most of MS-DOS itself in extended memory, so about 600K of the lower 640K