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For Xerox Internal Use Only -- February 2, 1977
SWAT February 2, 1977 1
Swat, a BCPL-oriented debugger
Swat is a debugger meant to be used with the ALTO operating system.
While many of its features are BCPL oriented, it can be used on any
NOVA code program. This document describes version 18 of Swat.
1. Invocat ion
Swat may be applied to any program running under the operating system
after it has been installed (see Installation below). There are four
ways of getting its attention:
(1) Press the lowest, right-hand key of the ALTO keyboard,
together with the (control) and (shift) keys at the left.
(2) Have your p~ogram execute the op-code 77400B.
(3) Invoke the Resume/S command (see below).
(4) Boot the file Dumper.Boot, normally by booting with the "DU"
keys depressed.
(5) Type (6) Call the function Ca11Swat. Up to 2 arguments will be printed
as BCPL ~trings. Thus CallSwat("No more memory")
2. Commands
The command has suffix action symbols, all control characters (e.g.
'tC). "n" is any BCPL expression (see Expressions below), "$" is escape
except where noted, "cr" means carriage return, ''If'' means line-feed.
2.1. Displaying cells
ntD prints the contents of n in decimal
ntI prints the contents of n as two 8-bit bytes
ntN prints the contents of n as a NOVA instruction
ntO prints the contents