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Calculators: Handheld: Rockwell the 18T

Size (approx): 75mm x 138mm x 16mm  (w,h,d)
Weight 90g excluding batteries
Power: 4.5V DC, 3 x AAA size batteries.  It accepts an adapter (undefined but 3mm plug, centre positive) through socket on the bottom side to the far left. 
Case: Super slim two-piece case in dark brown and beige matt plastic.  There is a large aluminium panel surrounding the keyboard with recessed on/off switch and brown plastic escutcheon.  Keys are typical of the Rockwell colour scheme but short travel with a load positive click.  The brand name is painted on the plastic whilst the model number and "on direction" (missing on this example) is printed in dark brown on the metal panel.  A neutral, flat and flush, wrap around display filter gives a nice bright display.
Display: 8 digit blue VFD, with a ninth digit for memory indication
Features: Standard four functions with percentages and two function memory.
Age: 1976/7
Manufacturer: Rockwell International, Microelectronic Product Division, Anaheim, CA 92803, made in Hong Kong.  Serial No. 11010-017
Comments: Nice slim hand held calculator that is well constructed.  The logic is sound but somewhat let down by seven digit negative numbers.  Original case is soft brown plastic with open top.  Very similar to the 20T which uses the same IC but with more functions available.

Components: 1 x cpu: square spiral design CF589 7642 (week 42 of  1976), 28 pin DIL. 0.6" width black plastic
1 x 9 digit flat face single tube VFD display
2 x transistors
7 x diodes
5 x capacitors
2 x resistor arrays
6 x resistors
1 x transformer
Boards: The main cpu board (18T 38P749 1P2751 Rev A Sh 2) is secured to the front by two plastic lugs and two screws.  It is connected via 13-way ribbon cable to to the keyboard board which is fixed using 7 plastic rivets.  The main board has a cut out to let one of the larger cylindrical capacitors sit half way through - and reduce the overall thickness.
Construction: Tricky.  From the reverse slowly separate the bottom and travel up one side pushing in the brown plastic to separate the the (two) lugs.  When complete do the other side and finally hinge off the top.

Logic comments: (CE) is used once to cancel the last number entered and (C) to clear the whole calculator.
There is automatic constant on all four functions
Input overflow is suppressed, inputting a ninth digit is ignored
Negative numbers are shown with a "-" to the immediate left of the number but as this does not travel into the ninth digit you are limited to seven digit negative numbers.
Overflow shows the result with "C" in the far left (ninth) digit and all decimal points alight. It is recoverable using (CE)
Divide by zero shows "C........0."  and is recoverable using (CE)
Memory is indicated by the lower right hand segment in the far left (ninth) digit - the only time this digit is used.
The memory is cleared by storing zero
No bugs detected