|Re: HP-15C LE Bug Reports|
Message #21 Posted by Mike Morrow on 16 Sept 2011, 7:24 p.m.,
in response to message #18 by Katie Wasserman
I cited this several days ago. However, rather than locking out the buggy old tests that can generate Error 9, it would be much more desirable to make them work on the 15C-LE, without always generating the Error 9 condition, and without corrupting memory.
The original self tests appear to actually test some things. The program memory corruption that I noted last week when ON plus * or ON plus + tests are performed seem to occur as memory is tested. It's not obvious why the old tests should be corrupting program memory. The problem could be potentially serious and it could still lurk, if the only solution to correct the problems with the old self tests is to prevent their initiation.
The new tests don't appear to test anything except:
1. All LCD segments can be activated, and
2. The firmware date, checksum, and copyright texts can be read from the firmware, and
3. The keyboard contacts can be tested.
With respect to the checksum shown in new self test 2, I wonder if that is a result of the test, or just a value stored in the firmware? What is shown for the 2011-04-15 firmware is FFFFh. (How likely is that?) It seems to be a number stored in firmware that has no real significance as a test. Especially when the checksum is a bogus and arbitrary FFFFh!