Browse Prior Art Database

Programmable Signal Loading Circuit

IP.com Disclosure Number: IPCOM000101467D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 4 page(s) / 113K

Publishing Venue

IBM

Related People

Curtis, BA: AUTHOR [+4]

Abstract

This article describes a circuit which allows a selectable number of input loads to be applied to any signal on a channel bus.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Programmable Signal Loading Circuit

       This article describes a circuit which allows a
selectable number of input loads to be applied to any signal on a
channel bus.

      Many computer systems, such as personal computer (PC) systems,
feature a bus or channel to which various options may be connected.
During testing of a computer system, it is desirable to determine the
system's response to having devices connected to the channel.  As the
number of input circuits (loads) on a given channel signal increases,
the circuitry which drives the channel must respond by providing more
current.

      In the past, actual options have been connected to the channel
to provide loading for test purposes.  This method has several
drawbacks.  First, the operation of the options might interfere with
the test.  In other words, since the options installed are fully
functional, and the system under test may be under various forms of
stress, it may be impossible to distinguish an option failure from a
system failure.  Secondly, there is no way to determine whether the
group of options chosen represents a realistic worst-case load to the
system.  Thirdly, this method cannot usually be applied to a
test-to-fail philosophy, as the system under test probably is
designed to operate under a typical load. Fourth, not all options
load all signals, and there is no way to isolate a particular signal
problem.  Finally, testing a system with different numbers of options
is awkward, as the system must be taken down, options added or
removed, and a configuration performed for each test.  The circuit
disclosed herein allows any number of input loads to be connected to
any or all signals on the system channel, with the number of loads on
each signal under control of a remote system.

      Fig. 1 shows the programmable load hardware configuration.  The
circuit of this disclosure is comprised of two main sections:  a
control...