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Cassette Motor Relay Wrap Circuit

IP.com Disclosure Number: IPCOM000050256D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Milling, PE: AUTHOR

Abstract

In diagnostic testing of computer hardware it is desirable to allow the microprocessor to isolate the cassette recorder from the processor's cassette input and output logic functions, and this may be accomplished by wrapping the output signal to the input hardware.

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Cassette Motor Relay Wrap Circuit

In diagnostic testing of computer hardware it is desirable to allow the microprocessor to isolate the cassette recorder from the processor's cassette input and output logic functions, and this may be accomplished by wrapping the output signal to the input hardware.

Referring to the figure, a double pole double throw (DPDT) relay circuit is used by the processor to turn the cassette tape recorder motor on and off. It also may be used for a cassette data wrap function. The cassette input circuitry is connected to the common contact of one section of the relay, and the line from the cassette recorder's external speaker output is connected to the relay's normally open contact. Further, the cassette output signal which goes to the auxiliary (AUX) or microphone (MIC) input of the cassette recorder is connected to the relay's normally closed contact. The other section of the relay used to turn on the cassette motor when the relay is activated. By providing the output data to the cassette output logic and checking in to see that it appears at the output of the cassette input logic, the processor can self-test the cassette hardware for correct operation when the motor is off, i.e., when the relay is not activated as shown in the figure. When the motor is turned on by moving the relay arms in a direction shown by the arrow, normal operation is enabled.

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