Use of DOS commands

Commands - Syntax

The available commands are entered without any special identification like usual BASIC statements.

Most of these commands can be used both in BASIC programs and in direct mode, i.e. for immediate execution from the screen.

However, a select few are limited to one mode or another. When exactly which command may be used is noted in the detailed descriptions.

In terms of syntax, the commands can be divided into three categories:

Commands that do not address a file:

command [parameter]

Commands that address a file:

command "filename" [,parameter]

Commands that address two files:

command "filename1","filename2"

Parameters are additional information required by some commands. If several parameters are required, they must be separated by commas.

A small restriction arises when using it within BASIC programs. The additional diskette commands are not recognized if they are specified directly after a THEN or ELSE in IF statements.

They must always be entered as an independent command either at the beginning of a line or after a command separator ":".

100 IF A= 1 THEN RUN "XYZ" wrong
100 IF A= 1 THEN :RUN "XYZ" correct

or

100 IF A <> 1 THEN 120
110 RUN "XYZ"
120 ......

File Types and Specifications

There are three different types of files in LASER-DOS:

  • BASIC program files

    with the label "T" as file type (= text file).

    BASIC programs are stored on the diskette in this file type.

  • Machine program files

    with the label "B" as file type (=binary file).

    Machine programs are stored on the diskette in this file type.

  • Data files

    with the label "D" as file type (=data).

    Your personal data is saved in this file type if you want to store it on the diskette from a BASIC program.

BASIC and machine programs are stored on the diskette in the same format. The different type designation is only in the table of contents and causes different handling when loading and starting.

Data files have a completely different structure, which means that there are also restrictions when using individual commands.

If you want to address a file on the floppy disk or create a new one, you must specify a file name in the commands, which is entered in the table of contents of the floppy disk.

A file name can be a maximum of eight characters long and can consist of any sequence of letters, characters or numbers.

In the commands, the file name must always be given in quotation marks. In contrast to other BASIC commands, the final quotation mark must not be forgotten, even if no further information is given.

Unfortunately, LASER-DOS does not allow using a string variable instead of the file name; this must always be specified in full directly in the command. This complicates the flexible handling of different data files. How you can still help yourself is noted in chapter 5 “Tips for programming”.