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Programmable Driver Current Interface for Personal Computer Systems

IP.com Disclosure Number: IPCOM000106147D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 105K

Publishing Venue

IBM

Related People

Aldereguia, AA: AUTHOR [+5]

Abstract

Described is an architectural implementation to provide a programmable driver current interface for high capacity personal computer (PC) systems. The programmable driver current interfaces a bus of expansion sockets so as to improve signal quality and system performance. The driver current interface is designed to match the memory or Micro Channel (MC) load, since the loads are dependent on the number of single in-line memory modules (SIMMs), or optional device cards installed.

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This is the abbreviated version, containing approximately 52% of the total text.

Programmable Driver Current Interface for Personal Computer Systems

      Described is an architectural implementation to provide a
programmable driver current interface for high capacity personal
computer (PC) systems.  The programmable driver current interfaces a
bus of expansion sockets so as to improve signal quality and system
performance.  The driver current interface is designed to match the
memory or Micro Channel (MC) load, since the loads are dependent on
the number of single in-line memory modules (SIMMs), or optional
device cards installed.

      Typically, a commonality of planar system circuit boards are
incorporated into a PC to support various types of processor cards.
The planar board contains channel expansion sockets, SIMM sockets and
basic input/output (I/O) functions.  The processor cards generally
contain functions, such as a central processing unit (CPU), memory
controller, direct memory access (DMA) and other functions.

      Although planar boards are designed to meet performance
objectives for a wide range of systems and, therefore, are designed
with common interface capabilities, system performance can be
constrained by the architecture used to attain commonality.  For
example, Fig. 1 shows a PC system planar designed with the MC
connectors, processor card connector and two banks of memory.  Each
memory bank contains four SIMM sockets with common signals for
address and data entry.  The MC has eight sockets driven with common
address, data, and control lines.

      When a system design calls for a reduction in the number of
signals, the number of the processor card connectors can also be
reduced and thereby requires less wiring.  The disadvantage is in the
memory subsystem interface which must drive from one to four SIMM
loads, depending on the configuration, thereby creating a large range
of capacitive loads.  However, the MC must drive from one to eight
option cards, depending on the configuration.  Operational problems
can exist when there are large variations in the amount of memory
installed, since it causes large capacitive load variations in the
memory circuits.  This large variation of loading can complicate
driver design.  If the drivers are designed to handle a large
configuration, such as four SIMMs per bank, then the...