Browse Prior Art Database

Self-Configuring Lookup-Table-Controlled DRAM Memory Controller

IP.com Disclosure Number: IPCOM000102265D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Hardell Jr, WR: AUTHOR [+3]

Abstract

Disclosed is a means for a memory controller to look up the timing parameters that match the system clock rate and the DRAMs that are plugged into a memory card. The memory controller will use a DRAM- type code and clock rate code to index into a lookup table to get the timing parameters. Using this method the controller can always run the DRAMs with the optimum timings.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 74% of the total text.

Self-Configuring Lookup-Table-Controlled DRAM Memory Controller

       Disclosed is a means for a memory controller to look up
the timing parameters that match the system clock rate and the DRAMs
that are plugged into a memory card.  The memory controller will use
a DRAM- type code and clock rate code to index into a lookup table to
get the timing parameters. Using this method the controller can
always run the DRAMs with the optimum timings.

      This method was developed for a memory card that can be put in
systems with different clock speeds.  The memory cards are
synchronous with the system (the CPU and the memory cards run on the
same clock).  The DRAMs are on SIMMs and the SIMMs are plugged in to
the memory cards.

      This method requires that the SIMMs have a code to indicate
SIMM size and speed.  The code bits will have pull-ups on the memory
cards.  The SIMMs will have the code bits open or grounded.

      The controller on the memory cards receive a DRAM-type code
from the SIMMs.  From the type code the controller can determine the
size, speed, and type of the DRAMs on a SIMM.

      Also in this method, the controller needs to receive a Refresh
Request pulse (clock) or a real time clock that is guaranteed to be
the same frequency in all systems that the memory card can be used.
The controller can determine the system clock speed by counting the
number of system clocks per Refresh Request or real time clock.  With
the DRAM and cloc...