Browse Prior Art Database

Fault Tolerant Refresh

IP.com Disclosure Number: IPCOM000107423D
Original Publication Date: 1992-Feb-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Aichelmann Jr, FJ: AUTHOR

Abstract

A structure is proposed that can provide allow for failures in the refresh control mechanism (i.e., counters) which will still maintain proper refresh operations.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 70% of the total text.

Fault Tolerant Refresh

       A structure is proposed that can provide allow for
failures in the refresh control mechanism (i.e., counters) which will
still maintain proper refresh operations.

      Conventional memory systems that use DRAM chips have to be
refreshed to retain the data.  A failure to maintain the proper
refresh interval can result in the data being lost. A failure within
the refresh counter mechanism can result in losing data within the
whole memory or a portion covered by a particular counter.  This
structure develops a fault tolerant refresh mechanism which can
detect failures and select an alternate refresh control path.  When
both refresh paths are bad, the refresh is lost.

      Fig. 1 depicts a block diagram of this proposed fault tolerant
refresh mechanism.  The counters are not shown and are well known in
the art.  There is an individual counter for each input to the
Refresh Error Detection Apparatus; each Refresh Error Detection
Apparatus has two paths.  The upper path generates the refresh
requests, while the lower path monitors and is used to detect a
refresh control/select error.  Fig. 2 shows the structure of the
"Refresh Error Detection Apparatus."  The refresh request signal path
is checked by the "path" with an XOR.  The XOR provides a counter
pair refresh error signal which overlaps the counter refresh signal
produced by the OR.  The latches in the two paths are set so that XOR
path is allowed to latch up based upon...