Radio Shack TRS-80 Model II Reference Manual page 54

Library Commands
To enter the debug monitor
Type:
DEBUG ON
DEBUG
While
DEBUG
is on, you can also enter the debug monitor simply by typing the
file specification of a user program.
TRSDOS
will load the program and
transfer control to the debugger. The transfer address for the program
will
be
in the PC register display.
ASCII display-
period "." indicates
a non-displayable
character.
RAM display-shows
hex contents of each
byte.
----
......
~----......--------­
Z-80A register contents.
SZHPNC are the flag bits
in register F.
Start address of one
16-byte "row" of RAM.
The? is the command prompt, meaning that you can enter one of the single-
key commands. Press (for "help") to display a "menu" or list of debugger
commands. To enter one of the commands, press the letter which is
capitalized in the command menu. For example, to enter the memory
command ("raM"), press
87