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Calculators: Handheld: Rockwell the 22K

Size (approx):

74mm (max) x 137mm x 14mm  (w,h,d)
Weight 94g excluding batteries.

Power: 4.5V DC, 3 x AAA size batteries.  Also accepts adaptor/charger (111R only) through a bottom side socket on the right. 
Case: Super slim three-piece metal case calculator with brushed aluminium finish and black plastic mid-piece. Black printed logo, model and keyboard border. Wrap around smooth black plastic display escutcheon with a neutral display filter is easy to read.  They keys are soft click, long travel and work well.  Soon all calculators would look like this.
Display: 8 digit blue VFD display – with a ninth used for minus and memory indicators.
Features: Basic four function with percentages, change sign, square root and four function memory
Age: 1976
Manufacturer: Rockwell International, Microelectronic Product Division, Anaheim, CA, USA.  Made in Japan, serial No. 102826.096.
Comments: A solid high quality calculator with a leading edge design that many were to follow into the early days of LCD calculators.  Original case is a wallet with pvc pockets for the calculator on the right and manual for the left.  Very attractive to this day and only let down by negative square roots.

Components:
Boards:
Construction: Unopened as there is a screw under the model sticker which I do not want to damage by removing.

Logic comments: The Clear key (CE/C) is used once to clear an input number and a second time to completely reset the calculator
Overflow on the input of a number is suppressed typing in a ninth digit is ignored
The automatic constant is on all four functions
The negative sign is shown in the far left (ninth) digit thereby allowing full eight digit negative numbers.
An overflow is shown with the result and all decimal points alight; it is recoverable using (CE/C).
A divide by zero error results in “0.0.0.0.0.0.0.0.” and is recoverable. Using (CE/C).
Negative square roots are allowed and result in a negative number.
The change sign key can be used in mid entry of a number
Memory storage is indicated by the far left (ninth) digit’s decimal point being on.

box

The attractive four colour printed box measures 177mm x 95mm and is 35mm deep.  Inside is a full box former to keep the whole thing stiff.  Made in Japan.

Whilst the box is big enough to accommodate everything and a set of batteries, my example has a line though the "batteries included" bullet point - I wonder if this was done by the retailer?

 

manual

The rather dull brown manual measures 121mm x 64mm and has 24 printed pages.  Whilst the cover is brown and black the insides are one colour black.  It has plenty of examples and is in English, German, French and Spanish. 

Ref 2520D-145 New 5-76 (1226R24-001)