Browse Prior Art Database

PRINTER Low Power Circuit

IP.com Disclosure Number: IPCOM000038852D
Original Publication Date: 1987-Mar-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Hovatter, MJ: AUTHOR

Abstract

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.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 80% of the total text.

Page 1 of 2

PRINTER Low Power Circuit

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. The power-down may only occur during an idle state in the printer adapter state machine which eliminates the possibility of any start/stop code violations. Fig. 1 illustrates the circuitry necessary to control the power- down state. Logically, if the gate signal is high, the printer adapter will be powered internal to the chip, and if the gate signal is low, the adapter will be depowered. The signal definitions for Fig. 1 are: A) + HOLD REGISTER EMPTY - this is active if the

parallel register which stores the data from the

processor has been passed to the transmit

register.

B) + XMIT SRL EMPTY - this is active if the serial

register which interfaces to the printer and is

loaded from the HOLD r...