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Calculators: Handheld: Sperry Remington 665

Size (approx): 80mm x 130mm x 27mm  (w,h,d)
Weight 170g excluding batteries


6V DC, 4 x AA size battery.  Also accepts adaptor (AD-4145), 0.18W, through a socket on the top side to the far right.
Case: Large two piece brick-shaped case made from two pieces of matt white plastic with rounded corners and edges.  The top is dominated by an almost flush neutral plastic section with a window for the display.  It has a black printed metallic sticker with the brand and model number in its own recess.  The keys are long travel with a hollow metallic sound, just like early Casio calculators of this era.
Display: 6 digit blue VFD with no seventh digit.  Lower segments used for zero.
Features: Four standard functions with display shift
Age: 1974
Manufacturer: Sperry Remington is a trademark of Sperry Rand Corporation.  Serial number 3042194 or 2140638 in battery compartment. 


I love this thick cased, rounded edge design.  Early 6-digit with shift display is novel.  Even more novel is the use of the lower segments only for the zero symbol.  For zero, it uses the lower half of what we would normally see an "8" displayed.  Logic is poor with no recovery, you cannot manipulate 12 digit numbers, negative zero bug, divide to zero bug and divide by zero counter bug - phew!  Sperry revised this model later in 1974 with a smaller case, the Sperry 667.

Components: 1 x cpu: NEC µPD178C K45286, 28 pin DIL 0.6" width black plastic
1 x single glass tube 6-digit VFD display
3 x resistor arrays
3 x resistors
12 x capacitors
1 x transformer Fuji UT 0627A, 4F17
Boards: The main processor board is the smaller of the two, held in place by an array of stiff wires to the key-board and the slotted display holder.  It is supported by three plastic posts.  The only ID signs are "KYDE1 LD8097 65-1 B".  The larger key-board is held in place, over the keys, with four screws.  ID marks are "KYDE1 6T-E4 A".
Construction: To open, undo the single screw hidden in the battery compartment.  Then gently lift the rear section away, hinging at the top.  Squeeze the sides of the case slightly to release tags.  Note that to save space the display sits on top of the cpu.

Logic comments: The (C) button is used to clear last entry of a number and (AC) to clear the whole calculator.
Overflow on number input is suppressed, keying in a seventh digit is ignored
An overflow shows the result and is not recoverable
Divide by zero results in a  "000000." which is also not recoverable, however, if you press the (>) key you will see a the clock counting
There is automatic constant on all functions functions
The arrow key lets you see the other six least significant digits but it then is unrecoverable
Negative numbers are flagged by a "-" sign in the sixth (on the far left) digit, limiting you to five digit negative numbers. Also, the least significant bit displayed will show the negative sign in the first digit.
It suffers the negative zero bug: key in (1)(-)(2)(=) to give "-1" now key in (+)(1)(=) to give "-0".
It also suffers the divide to negative zero bug: key in (AC)(-)(1)(=) to give "-1" then key in (/)(1)(0)(=)(=) etc... to eventually give "-0"

This image shows the main cpu board and dense component packing.  Notice the large transformer/power stepper unit to the bottom right that contains many components inside - it has a date code 4F17, the 17th February 1974.
Note the unusual way that zero is represented - by only using the lower half of the digit.  It is believed that this configuration would allow a single segment to go out and yet not confuse two different digits.