SYS (command)

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sys
Original author(s)Tim Paterson
Developer(s)Seattle Computer Products, Microsoft, Digital Research, IBM, Toshiba
Initial release1980; 44 years ago (1980)
Written inMS-DOS: x86 assembly language
Operating system86-DOS, MS-DOS, PC DOS, FlexOS, 4690 OS, PTS-DOS, SISNE plus, Windows, DR-DOS
TypeCommand
LicenseMS-DOS: MIT

In computing, sys is a command used in many operating system command-line shells and also in Microsoft BASIC.

DOS, Windows, etc.

SYS.COM (among other commands) in IBM PC DOS 1.0.

SYS is an external command of

boot loaders in the boot sector and DOS' IO system, these two files must reside in the first two directory entries and be stored at the beginning of the data area under MS-DOS and PC DOS. Depending on version, the whole files or only a varying number of sectors of the DOS-BIOS (down to only three sectors in modern issues of DOS) will have to be stored in one consecutive part. SYS will try to physically rearrange other files on the medium in order to make room for these files in their required locations. This is why SYS needs to bypass the filesystem driver in the running operating system. Other DOS derivatives such as DR-DOS
do not have any such restrictions imposed by the design of the boot loaders, therefore under these systems, SYS will install a DR-DOS boot sector, which is capable of mounting the filesystem, and can then simply copy the two system files into the root directory of the target. SYS will also copy the command line shell (COMMAND.COM) into the root directory.[6] The command can be applied to hard drives and floppy disks to repair or create a boot sector.

Although an article on Microsoft's website says the SYS command was introduced in MS-DOS version 2.0,[7] this is incorrect. SYS actually existed in 86-DOS 0.3 already. According to The MS-DOS Encyclopedia, the command was licensed to IBM as part of the first version of MS-DOS,[8] and as such it was part of MS-DOS/PC DOS from the very beginning (IBM PC DOS 1.0 and MS-DOS 1.25).

DR DOS 6.0 includes an implementation of the SYS command.[9]

Syntax

The command syntax is:

SYS [drive1:][path] drive2:

Arguments:

  • [drive1:][path] – The location of the system files
  • drive2: – The drive to which the files will be copied

Example

C:\>sys a:

Microsoft BASIC

SYS is also a command in Microsoft BASIC used to execute a

memory location where the executable code starts. Home computer platforms typically publicised dozens of entry points to built-in routines (such as Commodore's KERNAL[10]
) that were used by programmers and users to access functionality not easily accessible through BASIC.

See also

References

Further reading

External links