Radio Shack TRS-80 26-3650 Service Manual page 11

E.
Discrimination
Between
CPU
and
RAM
1
If
a test
unit passes
the
preceding checking procedures and
a
problem
still
exists,
follow the
calculations.
(1)
Manual Calculations
Below
Perform the following calculations
manually.
1
+
2X(3+4X(5+6X(7
+
8)))
Correct
answer
767
(In
DEG mode)
(TAN
(COS
(SIN
(LOG
100) )))
[EXE
Correct
answer
0.0174550616
If
the above calculations
cannot be made,
the
CPU may
be
faulty.
(2)
Program
Execute the following
program
after
pushing the
ALL RESET
button
on
the
bottom.
10
FOR
I
=
1
TO
2
:
FOR
J
=
1
TO
2
:
FOR K
=
1
TO
2
:
FOR
L
=
1
TO
2
20
NEXT
L
:
NEXT
K
:
NEXT
J
:
NEXT
I
30
GOSUB
40
:
PRINT "END"
:
END
40
GOSUB
50
:
50
GOSUB
60
:
60
GOSUB
70
:
70
GOSUB
80
:
80
GOSUB
90
:
90
GOSUB
100
100
GOSUB
110
110
RETURN
RETURN
RETURN
RETURN
RETURN
RETURN
:
RETURN
:
RETURN
After execution of
this
program,
display
should
show END.
If
the
above manual calculations
(1
)
are
done
but the
program
(2)
cannot be executed,
RAMI
may
be
faulty.
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