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Browse Prior Art Database

Circuit for Ensuring a Valid Programmable Option Select Identification For Personal Systems Adapters

IP.com Disclosure Number: IPCOM000120820D
Original Publication Date: 1991-Jun-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 78K

Publishing Venue

IBM

Related People

Chisholm, DR: AUTHOR [+5]

Abstract

Described is a circuit for ensuring that a programmable option select (POS) identification (ID) is valid as used with adapter cards in personal computer systems equipped with the Micro Channel* (MC). The circuit guarantees that a valid POS has been written before the system master interprets the POS ID as valid.

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

Circuit for Ensuring a Valid Programmable Option Select Identification
For Personal Systems Adapters

      Described is a circuit for ensuring that a programmable
option select (POS) identification (ID) is valid as used with adapter
cards in personal computer systems equipped with the Micro Channel*
(MC).  The circuit guarantees that a valid POS has been written
before the system master interprets the POS ID as valid.

      During the operational set up of a personal system, an adapter
card's POS ID is read to determine what is installed in the system.
If all zeros are read, additional time is allowed the adapter to
write a valid POS ID.  If the system reads a POS ID other than all
zeros, the assumption is made that the POS ID is valid.  However, if
the POS0 register is written by the local processor and the system
reads the POS ID before POS1 register is written, the system will
interpret this as a valid POS ID.  Since POS1 was never written, the
adapter will present an invalid POS ID to the system.

      The system will then look for this POS ID in non-volatile (NV)
random-access memory (RAM) which holds the system configuration data.
The POS ID will not be found and an error code will be displayed at
the terminal.  The system user will then look up the error code and
determine that a configuration error has occurred.  The user will
then attempt to reconfigure the system; however, the reconfiguration
program will fail since the adapter description file (ADF) for this
unknown adapter does not exist.  Since th...