Early
Electronic
Calculator		 Keystone 395 / exponent 1 Calculator

Manufacturer: Keystone
Model: 395 / exponent 1
Year: 1974
Form: Pocket
Functions: Basic four, percent, exchange, square root, memory
Number of Digits: 8
Display Type: PPX2
Display:Burroughs BR 09250 M (Panaplex II)
Logic Technology: LSI
Diodes: 34
Transistors: 13
IC Complement:Rockwell A1241PA
Batteries: 4 AA NiCd (1.2V each)
Power Connector:10.6 VAC, sub-mini audio
(alternate/no batteries: 4.5 to 6 VDC, + tip)
Tech. Data Level: 2
Tech. Data Source: RE
Tech. Data Pages: 1
Tech. Data:Schematic (pdf)

The Keystone calculators are quite rare in their use of gas-discharge displays in a pocket calculator.


The 325 came in a nice case, and with a mechanical pencil. The case is an indication of how valued such a calculator was in its day. The case does look suspiciously similar to those provided for electric shavers back in the day, though.

- Unit Log -

Serial Number: C377258
Year of Manufacture: 1974 (IC stamped with 7401, display with 7340.)
Accessories: With display case and manual.
Date of Receipt: 21 May 2001
Source: Elmer.
State upon Receipt: Good physical condition. Fully functional.
Current State: Fully functional (31 May 2001).

Date: 24 May 2001
Procedure: Cleaned.

Date: 31 May 2001
Procedure: 12 ohm dropping resistor on power supply input bypassed for use without batteries.


  Keystone 395 / exponent 1
Calculators | Integrated Circuits | Displays | Simulations
EEC 		bhilpert