This white and black calculator has black number entry and digit keys. It also has white arithmetic function keys, a clear entry/clear key, a percentage key, an x/y exchange key, and an equals key. Pushing a read function key allows one to switch the function of the white keys to memory keys, a square root key, an inverse key, and a square key . The display shows nine digits. The non-printing device has a sealed, rechargeable battery. It fits in a plastic sleeve.
A mark behind the keyboard reads: aPF MARK 23 (/) Electronic Slide Rule Calculator. A plaque on the back gives operating instructions. A mark on it reads: MARK 23 (/) Model No. Another mark on it reads: J-007440 (/) Serial Number. Another mark there reads: APF ELECTRONICS INC. (/) NEW YORK, N.Y. 10022 (/) MADE IN JAPAN.
A May 1976 advertisement in the Los Angeles Times lists the APF Mark 23 as regularly priced at $39.95 and on sale for $29.99.
Reference:
Los Angeles Times, May 28, 1976. p. D5.
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