Browse Prior Art Database

Overwrite Protection Method for FLASH Memory

IP.com Disclosure Number: IPCOM000105690D
Original Publication Date: 1993-Sep-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Hart, FP: AUTHOR [+3]

Abstract

A method is described for protecting critical system code stored in non-volatile memory from accidental or malicious modification by application programs. This method requires intervention by a human operator before any overwrite operation can take place.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Overwrite Protection Method for FLASH Memory

      A method is described for protecting critical system code
stored in non-volatile memory from accidental or malicious
modification by application programs.  This method requires
intervention by a human operator before any overwrite operation can
take place.

      The use of FLASH memory (non-volatile, read/write memory) to
store critical system software provides the system designer and
product engineer with considerable flexibility.  This software, such
as the Basic Input/Output System (BIOS), may change often during
system development.  Other changes may be desired after the system is
shipped to customers, to correct latent errors, or to add
enhancements to system capability.  By using non-volatile memory to
store this software, customers can be provided with a simple
application program which will update this memory.

      Used in this manner, however, the FLASH memory could also be
accidentally or maliciously modified by application programs, without
the knowledge of or assistance from the computer user.  There are
many instances of computer viruses in the public domain.  There would
be little qualitative difference between a "computer virus" which
attacks information stored on disk drives, and one which targets
information stored in non-volatile memory.

      To reduce the possibility of unauthorized modification of the
system code by application programs, a method has been devised which
requires...