And the annoying and inconsistent use of incandescent
bulbs for the power indicator and optical tape detector in
the 9830 . . when the main display is LED.
Indeed. I had to replace the former (but not the latter) in my 9830. I am told the LDR in
the tape sensor can
give trouble too, and it is a lot harder to find an indentical replacement for that than
for the bulb.
Another oddity is that the 9830 has the power-on indicator (a bulb and series resistor
across the 5V line)
whereas the 9810 and 9820 don't. In all cases the display is driven by firmware so it
is blanked under
certain conditions so it's not that you can use the display as a power-on indicator on
the smaller machines.
I like the power-on indicator of the 9815. It's a few ICs to display a row of dashes
across the display when
the display is not in use for displaying a number.
-tony