30 May
2015
30 May
'15
8:14 a.m.
Panaplex and other 7-seg gas discharge displays were
used in calculators up to the mid-70s. Actually one of the
last uses in a calculator might be the HP-9815 (1975/6):
http://www.cs.ubc.ca/~hilpert/eec/calcs/HP9815A.html
They were mostly used in desktops for the sake of the larger digit size but there were
some pocket/handheld
The Compucorp 320 series (and I assume 340 series, etc) used the same size Panaplex
display as the HP9815
(may even be the same part) although they were handheld-ish machines ( for those with big
hands ;-)) A little
earlier than the HP9815, so this does not invalidate your suggestion that the HP9815 was
the last calculator
to use one. To be pedantic, wasn't there are later version of the 9815 with 4K RAM on
the CPU board
(and no RAM expansion board) -- the 9815S or some such. That would probably be later than
the -A model.
When did the HP59304 HPIB display come out and when was it discontinued? It uses a 12
digit Panaplex display
calcs that used the smaller versoions. In calcs, they
were largely superseded by vacuum-flourescent displays
which were easier to drive, had a longer life, and could also be made with bright, large
digits.
I am surprised about the lifetime claim here. The VF display is a hot cathode device,
which tends to imply a
shorter life than a cold cathode part. VF displays were commonly used in consumer
electronics (VCRs, etc)
in the 1980s and 1990s over here, and uneven segment illumination due to low emission from
the filament
was a common fault. Conversely, my HP9815 and HP59304 are, AFAIK, still using the original
panaplex
display unit with no problems.
-tony