Browse Prior Art Database

Card Insert/Remove Detection using Two Phase Card Pins

IP.com Disclosure Number: IPCOM000104108D
Original Publication Date: 1993-Mar-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 2 page(s) / 79K

Publishing Venue

IBM

Related People

Ouchi, NK: AUTHOR

Abstract

Disclosed is the use of card pins with a resistive part and a conductive part which permits detection of when a card is inserted or removed. This permits a system to prepare for these events and minimize the time of outage.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Card Insert/Remove Detection using Two Phase Card Pins

      Disclosed is the use of card pins with a resistive part and a
conductive part which permits detection of when a card is inserted or
removed.  This permits a system to prepare for these events and
minimize the time of outage.

      In a high availability system such as DASD Arrays, it is
desirable to be able to repair the system while the system is
operational.  There are mechanisms that may allow insertion or
removal of a card while there is power on the system and the system
is running.  However, this may cause a disruption to the logic
signals or to the power levels.  Many systems are built around common
busses onto which the cards are inserted.  The insertion can cause
noise or loss of signal on the busses that may be so severe that the
error detection/correction mechanisms may be overwhelmed and errors
may go undetected or not corrected.  One mechanism to avoid some of
this impact is to warn the system that a change that may disrupt the
system is about to happen or is happening.  These usually require a
manual step such as an operator initiated command to the system.
This disclosure describes a mechanism that will permit a system to
detect that a card is being inserted or removed so that it can be
prepared and minimize the impact of the card change.

      The system detects the insertion or removal by changes in the
resistance of a set of special board contacts where the resistance is
initially low when the card is absent, resistance is high when the
card if partially inserted, and finally low when the card is
completely inserted.  Two pins with different lengths of high
resistive portions can be used to determine if the card is being
inserted or removed.  As illustrated in Fig. 1, the two phase...