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Electrically Erasable Programmable Read-Only Memory Update Condition Avoidance

IP.com Disclosure Number: IPCOM000100220D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Clarke, RR: AUTHOR [+3]

Abstract

A technique is described whereby the program updating of electrically erasable programmable read-only memory (EEPROM) devices are prevented from entering an endless loop condition. Through the implementation of a compare routine and an error reporting technique, an endless loop condition is avoided. A retry can then occur.

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Electrically Erasable Programmable Read-Only Memory Update Condition Avoidance

       A technique is described whereby the program updating of
electrically erasable programmable read-only memory (EEPROM) devices
are prevented from entering an endless loop condition.  Through the
implementation of a compare routine and an error reporting technique,
an endless loop condition is avoided.  A retry can then occur.

      Typically, computer systems use EEPROMs to contain information
and program codes for input/output adapter circuitry.  When update
information to the EEPROM is required and a malfunction occurs, such
as a stuck EEPROM bit, an endless loop condition can occur.

      Another unexpected endless loop can occur in that the
architecture requires that the subsystem be reset following operation
of the update utility.  The update utility can be loaded even though
no updates are required.  This is caused by a faulty compare routine.
 If the utility is loaded and finds that no updates are required, a
reset to the subsystem will cause the utility to be loaded again.  An
endless loop on one subsystem may prevent the entire system from
continuing its initial microcode load (IML).

      To overcome the above condition, two types of error reporting
are required.  First, the method verifies the need for updating by
checking an imbedded part number within the EEPROM.  If the part
number within the EEPROM is not the same as the part number in the
new EEPROM code, the EEPROM is updated, otherwise no change is made.
This compare verification process assures that by changing the part
number information last, it confirms that another update will take
place should the first update have failed for some reason.  Update
failure is reported and indicates the first type of error reporting.

      If the compare routine i...