BASIC-DOS

Configuring BASIC-DOS

System Configuration

When BASIC-DOS starts, it automatically allocates enough memory for:

• Up to 20 open files at a time
• Up to 4 active sessions at a time

and it creates a single 80-column, 25-row console, running COMMAND.COM.

Those settings, along with others, can be changed through entries in a special file named CONFIG.SYS on your BASIC-DOS startup diskette. Each entry is a line of the form KEYWORD=value. Lines that don’t begin with a recognized keyword (eg, lines beginning with REM) are ignored.

For example, if the following lines appear in CONFIG.SYS:

FILES=30
SESSIONS=8

then memory will be set aside for up to 30 simultaneous open files and up to 8 simultaneous active sessions.

The recognized keywords are:

• BOOTKEY
• CONSOLE
• DEBUG
• FILES
• MEMSIZE
• SESSIONS
• SHELL
• SKIP
• SWITCHAR

Installable device drivers (DEVICE=) aren’t supported yet.

BOOTKEY

BOOTKEY=key

Acts as if key had been pressed at the BASIC-DOS boot prompt. This is a debugging aid: DEBUG builds of BASIC-DOS use the boot key to enable additional diagnostic messages. It has no effect if a key other than Enter was actually pressed.

CONSOLE

CONSOLE=CON:cols,rows[,x,y[,border[,adapter]]]
CONSOLE=CON:cols,rows,BIOS
CONSOLE=COMn:baud,parity,databits,stopbits

Defines a console for a session. Each CONSOLE line defines a console for the next session, so a CONSOLE line is needed for every session that has its own console; the number of CONSOLE lines can’t exceed SESSIONS. If there are no CONSOLE lines, a single console is created, as if CONSOLE=CON:80,25 had been specified.

For a CON console:

• cols and rows are the size of the console (up to 80 columns and 25 rows)
• x and y are the column and row of the console’s top left corner on the screen (default 0,0)
• border is 1 to draw a border around the console, or 0 for none; a border uses the outermost rows and columns of the console
• adapter is 0 for the primary video adapter, or 1 for a second adapter (eg, a machine with both an MDA and a CGA)

BIOS (or just B) following rows creates a full-screen console that writes characters using the BIOS (INT 10h), rather than directly to video memory.

A COM console uses a serial port (eg, a terminal connected to COM1) for both input and output.

Two consoles side by side, each 40 columns wide with a border:

SESSIONS=4
CONSOLE=CON:40,25,0,0,1
SHELL=COMMAND.COM
CONSOLE=CON:40,25,40,0,1
SHELL=COMMAND.COM

DEBUG

DEBUG=device

Sends diagnostic messages from DEBUG builds of BASIC-DOS to the specified device (eg, DEBUG=COM1:9600,N,8,1,0).

FILES

FILES=n

Sets the maximum number of files (and devices) that can be open at once, across all sessions. The default is 20, and n can range from 8 to 255.

MEMSIZE

MEMSIZE=n

Limits the memory that BASIC-DOS uses to n kilobytes (16-640), assuming the machine has at least that much memory. This is mainly used for testing BASIC-DOS with different amounts of memory; it doesn’t reserve memory for individual sessions, since all sessions share the same memory.

SESSIONS

SESSIONS=n

Sets the maximum number of sessions that can be active at once. The default is 4, and n can range from 1 to 32.

Sessions are used not only by consoles, but also by pipes: every command after the first in a pipeline runs in its own session. So SESSIONS should allow for at least one more session than the number of consoles.

SHELL

SHELL=program [command[:command]…]

Specifies the program to run in the next session, along with any startup commands. Each SHELL line starts a session, using the consoles defined by CONSOLE lines in order. If there are no SHELL lines, COMMAND.COM is run in the first session.

BASIC-DOS doesn’t automatically run an AUTOEXEC.BAT file, so a session’s startup commands must be specified on its SHELL line, separated by colons:

SHELL=COMMAND.COM COLOR 7,1:AUTOEXEC.BAT

SKIP

SKIP=device[,device]…

Lists built-in device drivers that should not be loaded, using their exact device names (eg, SKIP=CON,FPU$). A skipped driver is never initialized, and its memory is reclaimed.

For example, a configuration that uses a serial console doesn’t need the CON driver, and skipping the FPU$ driver disables floating-point support (so variables default to integers, and / and ^ become integer operations).

SWITCHAR

SWITCHAR=char

Changes the character that introduces command options (switches) from / (the default) to char (eg, SWITCHAR=-, so that DIR -P is used instead of DIR /P).

Sample Configuration

This CONFIG.SYS runs a single session on a terminal connected to COM1, without loading the CON driver:

REM Demonstration of a single-session configuration
SKIP=CON
SESSIONS=3
CONSOLE=COM1:9600,N,8,1
SHELL=COMMAND.COM AUTOEXEC.BAT

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