Owner`s manual

Page 6-9Setting up Your System
One of the common uses of SYSTEM in the system initialization command file is to
include the AlphaBASIC runtime package (RUN.LIT or RUNP.LIT) in the monitor so
each user does not need to load RUN into his or her own memory partition. You may
also include the interactive compiler (BASIC.LIT) itself if you expect heavy development
work by more than one user. If users on your computer will be making extensive use of
the screen-oriented text editor VUE, you may want to load it into sharable memory by
using the SYSTEM command.
It is important to load the device driver program of any peripheral devices you have
connected to your computer into system memory, so programs can access that device.
Peripheral devices include disk drives, floppy drives, backup devices, etc.
Another reason to use the SYSTEM command is if you want to include frequently-called
user subroutines in the monitor. You can locate such subroutines by name from
assembly language programs by using the SRCH and FETCH monitor calls. Again, if
these programs are to be shared by several users, they MUST be re-entrant.
To include programs in the system monitor, use one SYSTEM command for each
program. Follow each SYSTEM command with the file specification of the program you
want to include. For example:
SYSTEM VUE.LIT
SYSTEM RUN.LIT
SYSTEM STR.DVR[1,6]
If your file specification does not include an extension, the monitor assumes a .LIT
extension; if you don’t supply an account specification, the monitor assumes account
DSK0:[1,4].
You must place any SYSTEM commands after all other commands in the system
initialization command file that expand the monitor size.
The SYSTEM command has another use beside the inclusion of programs in the
system monitor. A SYSTEM command alone on a line in a system initialization
command file (that is, not followed by a file specification), tells the system that monitor
expansion is finished. The computer then flags the monitor as up and running. The
computer also sets a flag in the system communication area indicating the system
initialization is done except for final cleanup. Various commands (including SYSTEM)
test this flag to see which mode to operate in.
For example, before the computer is up and running, the BITMAP command defines the
disk bitmap areas in the monitor; after system initialization, the BITMAP command
displays the memory locations of those bitmaps.
Whether or not you include any programs in the monitor, your system initialization
command file MUST have a SYSTEM command without a file specification to tell the
operating system the computer has been initialized. This blank SYSTEM command
must be listed after any other commands that expand the monitor size (including any
other SYSTEM commands).
System Operator’s Guide to the System Initialization Command File, Rev. 03