Mixed Bag of Sid: Disk Operating System (DOS)

Disk Operating System (DOS)

CP/M written by Gary Kidall from Digital Research dominates the market.

CP/M = Control/Computer Program/Monitor.

In 1979, Tim Patterson developed Q DOS (Quick and Dirty Operating System)
Microsoft bought the rights to Q DOS for $50,000 keeping the IBM deal a secret from seattle Computer Products.
Microsoft made slight changes to Q DOS and then presented ” Microsoft Disk Operating System” or MS-DOS to IBM.
IBM Pc was announced in August 1981,with version 1.0 of MS-DOS.
More than 50 other hardware manufacturers also used DOS, after IBM selected MS-DOS.
DOS was a command interface and it was not case sensitive (CAPS).
File names can be no longer than eight characters and extension, which is optional, can be up to three characters long.
No Spaces or other illegal characters (` ‘ [ ] | < > + = ; , * ? ) can be used in the file name or extension.
The File name and extension are separated by a period, or ” dot . ” and this naming system is know as the “eight dot three” (written as “8.3″) system.
Examples of DOS filenames= word.exe , system.ini , Animal eater.doc
DOS cannot support more than two floppy drives and are assigned drive letters A: and B:
Hard drives start with the letter C: and can continue to Z: if necessary.
DOS uses a hierarchical directory tree to organize the contents of these drives.
DOS operating system is composed of three main files IO.SYS , MS DOS.SYS and COMMAND.COm
IO.SYS handles all the talking to the BIOS and hardware.
IO= Input Output
SYS= System
MS DOS. SYS is the primary DOS code, often called the kernel.
COMMAND.COM actually interprets commands typed into the computer and passes that information to MS DOS.SYS . It is also called the shell or command interpreter.
IO.SYS It is a system file it loads itself into the machine and then checks the Input Output System configuration.
MS DOS.SYS = It is a system file and an actual DOS Code.
COMMAND.COM . It is a command line file it holds all the commands used in DOS.