Estex: Disk SubSystem (DSS) - Overview

1. Introducing
2. Booting
3. System console
4. File System

1. Introducing

    Estex is an operating system for the Sprinter computer, which includes various modules. This document contains the overview of the module of a disk subsystem.
    DSS has File System same as at FAT16, and full compatible with it.

2. Booting

    After you switch power on or reset your computer, the BIOS try reading system bootstrap from 1-st sector of a boot disk.
    When booting from a diskette or a hard drive, the boot sector is first to load and execute, and it in turn loads the module of a disk subsystem SYSTEM.DOS.
    At the end of the start sequence the operating system performs the following steps:

• initialization disk subsystem and displayed message "Starting DOS..."
• loads System Console SYSTEM.EXE
• runs the commands and programs listed in SYSTEM.BAT

3. System console

    In DSS, a lot of everyday work is done in a command line interface called a system console. A console main job is to take commands from the input channel and execute them. Also have built in functions to help everyday tasks such a file management, file globing, command line editing and environment variables.
    The system console allows the user to interact with the operating system. For DOS, the system console is SYSTEM.EXE. When you see the command line prompt (i.e. A:\> or C:\>), you know that SYSTEM.EXE is loaded and active. When you enter a command line, the processor parses (interprets) the command and attempts to determine a proper response.
   The system has the ability to use environment variables in batch files. These variables can be referenced by surrounding the variable with percent symbols (%).

for example:

SET WORKDIR=C:\WORK\FILES\DOCS
COPY %WORKDIR%\file.ext b:\file.ext
COPY %WORKDIR%\file.zip b:\newname.zip

    Today, the following commands are available in system console:

CD	Displays the name of or changes the current directory.
CHDIR	Displays the name of or changes the current directory.
CLS	Clears the screen.
DATE	Displays or sets the date.
DEL	Deletes one or more files.
DIR	Displays a list of files and subdirectories in a directory.
ECHO	Displays messages, or turns command echoing on or off.
ERASE	Deletes one or more files.
EXIT	Quits the SYSTEM.EXE program (command interpreter).
HELP	Provides Help information for console commands.
MD	Creates a directory.
MKDIR	Creates a directory.
PAUSE	Suspends processing of a batch file and displays a message.
PATH	Displays or sets a search path for executable files.
RD	Removes a directory.
REM	Records comments (remarks) in batch files or SYSTEM.BAT.
REN	Renames a file or files.
RENAME	Renames a file or files.
RMDIR	Removes a directory.
SET	Displays, sets, or removes Estex DSS environment variables.
TIME	Displays or sets the system time.
VER	Displays the System version.

4. File system

    Today, Estex Disk Subsystem used FAT12 and FAT16 as file system. The File Allocation Table (FAT) file system organizes data on fixed disks and floppy disks.
    And it have the following form for valid file specification:

[drive:][directory\]filename[.ext]

    The file specification is a string, containing a names of disk, directories separated by a symbol "\" and name of file. The names of disk drive and directories can be missed. If required file placed in current directory.

for example:

C:\TEXT\DOC\text.doc

A:file.txt

\TEXT\info.txt

    The DSS used letter followed by a colon (:) as names of disk devices (A:, B:, C: etc.) The name of disk can be typed before filename for specified working disk. For example: command DIR C:TESTFILE searches for TESTFILE in the current directory of disk C:. When disk name not specified DSS used current disk. At start DSS, the current disk is a disk whence was loaded DSS.
    The filenames consist of two parts. The first part contain 8 letters, digits, or the following special characters: $ % ' – _ @ { } ~ ` ! # ( ). The second part is not necessary and contain any combination of up to three letters, digits, or special characters, preceded by a period (.). For example: the names "NAME" and "NAME." is specified same file. In the filename don't allows symbols with codes less 32 and chars . " / \ [ ] : | < > + = ; ,
    As the subdirectories files too, their names are formed by same way.
    The name of root directory always "\". And each subdirectories contain two items with names "." and "..". The name "." specified a current directory and name ".." specified name of parent(uplevel) directory.
    Some console commands and DSS functions allow to use global symbols ? and * which can be used for filename templates.
    The symbol ? means that any one char of filename. The symbol * means that it char can be replaced by any symbols.

for example:

*.txt     - means, all files with type "txt"
a??.*     - means, files which contain three or less symbols and first symbol is "a"
dc*.exe   - means, files with type "exe" and began "dc"

    The filenames do not distinguish between uppercase and lowercase letters.