Hardware manual

6.4. Miscellaneous information
The key in the lower right corner of the keyboard on a Microswitch keyboard (<blank-bottom>) or in the
upper right on an ADL keyboard (FR1) is called the Swat key. If you press it, as well as the <ctrl> and
<left-shift> keys, the Swat debugger will be invoked. If you do this by mistake, <ctrl>P will resume your
program without interfering with its execution, and <ctrl>K will abort your program.
You can force an abort at any time by depressing the Swat key together with the <left-shift> key.
In order for the operating system to run properly, the following files should be on your disk (those marked
* are optional):
SysDir System directory.
DiskDescriptor Disk allocation table.
SysFont.Al System display font.
Executive.Run Executive (command processor).
Sys.Boot Boot-file containing the operating system.
Sys.Errors * Error messages file.
Swat * Debugger program, created by running InstallSwat.
Swatee Debugging file essential to Swat.
(Note: If you wish to change the font used by the operating system, it suffices to copy a new font to
SysFont.Al and boot the system.)
If you intend to write programs that use the operating system facilities, you will want some additional files:
Sys.Bk Required by Bldr to load programs that reference operating
system functions. This file also shows which functions are
implemented in which levels and the names of source files for
the code.
SysDefs.d Definitions of standard system objects. You will probably want
to "get" this file in Bcpl compilations that use operating system
functions extensively.
Streams.d Data structure definitions relating to streams.
AltoFileSys.d Data structure definitions relating to files.
Disks.d * Data structure definitions relating to the "disk" object.
AltoDefs.d Definitions of places and things peculiar to an Alto.
BcplFiles.d * Definitions of the formats of Bcpl-related files.
Alto Operating System May 5, 1980 29
For Xerox Internal Use Only -- December 15, 1980