Test Operations; Repeating Test - HP -28S Manual

Test Operations
There are two system operations for testing the calculator. The first is
a repeating test of the electronics, which runs without assistance. The
second is a keyboard test, which requires you to press all the keys in a
specified sequence. Both tests perform a System Halt.
Repeating Test
To perform the repeating test:
1. Start the test.
a.
Press and hold 1
ON
I.
b.
Press~.
c.
Release 1
ON
I.
2. The display shows horizontal and vertical lines, a blank display,
a random pattern, and then it briefly displays the result of the
test before starting over .
• The message
OK-2S:::
indicates that the calculator passed the
test.
• A message such as
1 FA
I L indicates that the calculator failed
the test. The number indicates the nature of the failure.
If you interrupt the test by pressing a key, the test returns a
failure message because it didn't expect any keystrokes. Such a
failure message doesn't indicate a problem with the calculator.
3. Exit the test by performing a System Halt.
a. Press and hold 1
ON
I.
b.
Press []].
c.
Release 1
ON
I.
218 25: System Operations