The Oldest Calculator i repaired

its called 'Canon Palmtronic 8M'  

 this is great. what I'm wondering is  it has florescent display working with 2nos 1.5V AA battery.

this is what i fond spec from the NET,

Size (approx):	77mm x 142mm x 20mm (w x h x d) Weight 118g not including batteries.
Power:	3.0V DC using 2 x AA size batteries.  It accepts an adaptor (3V DC 0.4W) through a socket on the top side to the far left.
Case:	The case is two-piece mottled black plastic.  It is brick shaped with rounded front vertical edges and a full-ridged design on the front top area.  A metallic gold and black label bears the make and model number and sits in its own recess.  The keyboard surround is shiny brushed aluminium.  The neutral display filter is flat, flush and shaped like the case and gives a clean bright image.  The springy keys are long travel with a soft click and work very well.
Display:	8 digit blue VFD with a ninth digit for negative, error and memory indicators.
Features:	Standard four functions with percentages, square root and four-function memory.
Age:	est. 1976
Manufacturer:	Canon Inc., made in Japan.  Serial number from the sticker on the inside of the battery cover is 450885.
Comments:	Nice feeling quality calculator with a design that covered quite a few models.  This Type I is easily recognized by the ten ridges above the display but is otherwise very similar to the case of the Type II.  The logic is OK with an odd recovery system but let down by negative square roots and input overflow.  The original case if soft black plastic, open top with front and rear cut outs.  It is embossed Canon on the front and Japan on the back, but looks a little too small.