Radio Shack TRS-80 User Manual page 167

Chapter 26
DEBUGGING PROGRAMS
Quick-
the
RAID!
By
now,
the
Computer
has given
you
plenty of nasty messages
like
WHAT?,
HOW?
and
SORRY.
You know
something's wrong, but
it
isn't
always obvious
exactly
where, or why.
How
do you
find it?
The answer
is
simple
—
Be Very
Systematic.
Even
experienced
pro-
grammers make
lots
of
silly
mistakes
,
.
.
but
the experience teaches
how
to locate mistakes
quickly
.
Hardware, Cockpit
or
Software?
The
first
step in
the "debugging" process
is
to
isolate
the
problem
as
being
either
1)
A
hardware problem,
2)
An
operator problem,
or
3)
A
software
problem.
1
1
i
Is it
Farther
to Ft.
Worth
or
By
Bus?
Starting
with
the least likely possibility
—
is
the
Computer
itself
working properly?
Chances
are
(and our fondest
desire
is)
that the
Computer
is
working
perfectly.
There
are several very
fast
ways
to find
out.
A.
Type
PRINT MEM
1
or
just
P.
Mi
If
there
is
no program
loaded into
memory,
the
answer should
be
3583
If
there
is
a
program loaded, the answer should
be
some
value
LESS
than 3583.
If
the answer
is
MORE
than
3583
(assuming of course
you
have not
added more
Radio Shack
RAM),
there
may
be
trouble.
Or,
it's
possible that the
answer
is
a
NEGATIVE
number
. . .
same
solution.
m. 7679 (8K
machine);
1$%?1
&&$&
That's
Random
Access
Memory.
165