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Using a High Density Erasable Programmable Logic Device for Real Time Error Logging in Memory Testers

IP.com Disclosure Number: IPCOM000114116D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Eigner, JM: AUTHOR

Abstract

Disclosed is a circuit design (Figure) for Real Time Error Logging (RTEL) that can be used for memory testing. It provides circuitry to capture and store fail information for run-to-completion testing. The errors are discarded with the reset function.

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Using a High Density Erasable Programmable Logic Device for Real
Time Error Logging in Memory Testers

      Disclosed is a circuit design (Figure) for Real Time Error
Logging (RTEL) that can be used for memory testing.  It provides
circuitry to capture and store fail information for run-to-completion
testing.  The errors are discarded with the reset function.

      RTEL Circuit - This circuit can be used for testing memory
devices.  It provides error logging capabilities for run to
completion testing.  The circuit should be replicated for each I/O of
each memory device under test.  This circuit will capture an error
and hold it until the circuit is reset.
  This circuit provides a simple, cost effective solution for memory
   testing.

      RTEL Circuit Description - This circuit uses 9 flip flops and
surrounding combinatorial logic to implement a 1 bit x 8 deep RTEL.
This piece can then be repeated throughout the device to form a wider
RTEL suitable for testing a wide memory card.

      Functional Description - The device select lines are tied
directly to a group of memory card address lines.  They provide
decode for 1 of 8 I/Os on the corresponding DRAM I/Os.  The net
result is each I/O on each DRAM has a corresponding flip-flop in the
RTEL.  If a miscompare happens at the XOR (eXclusive OR), the
selected flip flop gets set.  It will remain set until the -Clear
signal resets it.  Each bit can be masked as well to disable the
compare from se...