5 Sep
2007
5 Sep
'07
11:10 p.m.
Jason T wrote:
> I've got a line on one of these old
Nixie-tube calculators at
> a fair price. I know they used an outboard processor, making
> them little more than (very pretty) terminals to a central
> CPU. Are they of any use other than a doorstop or eye candy
> for the collection? (And don't say "harvest them for the Nixies!")
Rick Bensene wrote:
The 300 - Series Wang Calculators consisted of two
parts: an electronics
package, and
"Keyboard/Display Units". The electronics packages are usually
small-briefcase-sized (single-user) or longer, shorter packages with a
connector (or connectors for the multi-user versions) that the
keyboard/display units plug into.
The Keyboard/Display units are pretty much useless by themselves -- they
need the "brains" in the electronics package to do anything. All the
keyboard/display units consist of are a keyboard and keyboard encoding
circuitry, and a Nixie tube display with display decode/driver
electronics. There are no mathematical electronics in the
Keyboard/display units.
...
The keyboard/display units have pretty simple
circuitry inside them. It
wouldn't be too hard to build some kind of microprocessor or
microcontroller-based gizmo that would emulate the electronics package
and bring a Keyboard/Display unit to life. You'd need some good math
knowledge to implement the various math routines, but the interface is a
very simple multiplexed BCD display, and a six-bit key code for each
key, encoded by a diode matrix.
I received two orphan 320K keyboard/display units a few years ago (no logic unit).
Hobbled up a little level-shifting hardware and wrote some calculator code to
drive them from a SWTPC 6800 - in other words the 6800 was replacing the
missing logic unit. Worked fine but the next (intended) step was to redo it
all in a microcontroller and stuff it inside the 320K case so it would be a
stand-alone 'modern' nixie desktop calculator. Would be kinda nice because the
320K KDUs have a small footprint compared to other nixie desktop calcs. There
is very little spare room in the case however. I think I anticipated it would be
feasible if one used an external wal-wart (ugly) for the power transformer.
The KDUs are very well built: cast aluminum case, micro-switches for the keys...