Another subtle HP-15C CE difference

[rprosperi]

(10-19-2024 07:20 PM)naddy Wrote:  I just noticed another tiny difference between the CE and the original 15C:

When you run the 1L self-test on the CE to turn on all display segments, this includes the low battery indicator. By comparison, the corresponding end of the ON/× test on the original Voyagers does not turn on the battery indicator.

If this has been mentioned before, it's not mentioned in Gene's pinned summary.

Nice catch, and interesting observation!

The original classic Voyager test sequence is run by the original ROM code, turning on various combinations of LCD segments (or all at once) but never the low-power segment, likely to not mislead the user about battery conditions, but possibly that segment was controlled independently. I always thought the original [ON][/] sequence (lighting various segments for each key) weak as one can't tell what might be missing, whereas the [ON] [X] sequence lights them all, so easy to see if something is missing.

The 15c CE test sequence on the other hand is done by the emulation layer code, turning on all segments independently of the original ROM code, and this code simply ignores the old sequence, as can be seen by it's different approach of turning all on and then turning them off via pressed keys, which is more useful IMHO.

More than likely, the author of this new code never even noticed this subtlety.