Browse Prior Art Database

Bus Interface/Control Circuit

IP.com Disclosure Number: IPCOM000122478D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Knox, AR: AUTHOR

Abstract

Disclosed is a control circuit employed in a time-of-failure display monitor stress tester described in the preceding article. The circuit allows interfacing of a PS/2* control tester with up to six 16-channel input cards as well as providing error detection, protection, and allowing manual system control.

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

Bus Interface/Control Circuit

      Disclosed is a control circuit employed in a
time-of-failure display monitor stress tester described in the
preceding article.  The circuit allows interfacing of a PS/2* control
tester with up to six 16-channel input cards as well as providing
error detection, protection, and allowing manual system control.

      The purpose of this circuit card is: first, to provide an
interface to/from the PS/2, control the six 16-channel input cards
(described in the preceding article); secondly, to allow manual
control of the system and also to provide hardware error detection in
case of software programming errors leading to potentially
destructive conditions arising.  The I/O card in the PS/2 is
configured as one 8-bit output port and one 16-bit input port.  The
eight output bits are used for bank selection and the self-test
functions.  The 16 input bits to the PS/2 are a word-wide data bus
where the status of each detector connected to each of the 16-channel
input cards is successively applied to this bus.  The logic is
designed such that if the control signals from the PS/2 become
disconnected, no 16-channel input cards are enabled.  Also, during
power up of the system the same condition holds.  The buffers from
the backplane to the PS/2 are permanently enabled.

      For diagnostic purposes, the system may be run manually using
switches on the front of the control card.  Using these, it is
possible to drive either of the self-test signals high or low and to
select the active 16-channel input card.  The manual control has
precedence over that from the computer.  When switched to manual, the
control card disables the control signal buffer from the PS/2 to
prevent damaging signal contentions.  However, the error de...