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PRINTER Low Power Circuit Disclosure Number: IPCOM000038852D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01

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Hovatter, MJ [+details]


A circuit is described which enables the printer adapter logic to consume less power. The natural state of the printer adapter is maintained during power down. The low power circuit for a printer allows the printer adapter circuitry to power down to the low power mode if the HOLD REGISTER and the TRANSMIT REGISTER are empty and the printer is in the standby or off mode. The HOLD and TRANSMIT registers are emptied only by shifting the contents out of both registers as in the normal operation. The safeguard of only allowing the power-down condition when both registers are empty precludes any application program from misinterpreting the printer status and prevents the printer from sending an error signal on power-down which would trigger an interrupt.