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Calculators: Handheld: Sperry Remington 821-GT

Size (approx): 92mm x 149mm x 36mm (max)  (w,h,d)
Weight 206g excluding batteries


6V DC, 4 x AA size batteries.  It accepts an adapter (AD-4145 0.23W) through a socket on the top side on the far left.  The on/off switch is three position to switch on the memory.
Case: Two-piece matt black and gloss beige plastic which is quite large with rounded edges and corners.  The neutral display filter is flat and slightly inset.  Below this is a full width and corner brushed aluminium panel which is printed blue and black and sits in its own recess.  The keys are long travel, squishy and have a hollow click like early Casio's and work OK with a bit of switch bounce.
Display: 8 digit blue VFD, no ninth digit, lower segments used for zero (see below).
Features: Standard four functions, with "T" (for Total recall memory) and secondary equals. This is a funny way of having a three function memory.  Display shift function.
Age: 1974
Manufacturer: Sperry Remington is a trademark of Sperry Rand Corporation. Made in Japan.  Serial No. 2114603 is inside battery compartment.


Lovely early hand held calculator.  The eight digit, switchable to 16 digit display is archaic but the calculator is well built so quite loveable.  Little-used system of lower half digit for zero display.  Very similar to some early horizontal Casio calculators such as the Casio Mini Memory.  It is very similar to the Sperry 823-GT inside so the cpu has a percentage function not accessible in this model.

Components: 1 x cpu: Hitachi HD3654 4G11 (11 of July 1974), 36 pin DIL, 0.6" width black plastic
1 x 8 digit single tube VFD display
2 x transistors
5 x diodes
16 x capacitors
3 x resistor array
7 x resistors
1 x transformer: Fuji UT 0633 Pat No. 427559
Boards: The keyboard assembly (Ref B8Z-E4-2A IS-1) is joined to the front by five screws.  This attaches to the main cpu board (Ref A8Z-1A LD8103) via a row of 11 stiff wires.  This sits lose in the lower section of the case.
Construction: Remove the single screw from the back and the whole front of the case lifts off by gently squeezing the lower half to release the lugs.  Pull the front up, hinged around the top of the calculator.

Logic comments: (C) is used once to cancel the last number entered and (AC) to clear the whole calculator.
There is automatic constant on all four functions
Input overflow is suppressed, inputting a ninth digit is ignored
Negative sign is shown in the immediate left hand digit thereby limiting you to fifteen digit negative numbers.  
The right arrow key is used to toggle the view of the least and most significant digits.
Divide by zero shows no error - just zero. 
Overflow is shown by the calculator hooking up - you may still use the arrow key to view the full result - but It is not recoverable
Switching the on/off button into "T" will switch on the accumulation memory.
Pressing the black equals will accumulate the memory by adding (black equals) or subtracting (red equals).
The "T" key recalls the memory without clearing it.

The manual on the right is for this model and the 823-GT.  It is approx 130mm x 92mm 12pp one colour black.

Well written manual with plenty of examples and clear descriptions.

Printed in Japan


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.