Packard Bell Nec

Zenith Data Systems Corporation

Terence Paul O'Brien

Mark D Nicol

Jimmy Dean Smith

Brian K Straup

Mark L Herman

Michael P Krau

Richard David Ball

Terrence A Hussey

The present invention relates to a computer system and more particularly to a computer system which allows option controller cards for various input/output (I/O) devices to be added on the motherboard at minimum cost.

Expansion module including programmable chip selects

Programmably selectable addresses for expansion cards for a motherboard

System for establishing a transfer mode between system controller and

Manual insertion of hardware jumpers to configure I/O device selection and addressing is eliminated through the implementation of specialized hardware which allows for program control over several addressing paths. A register file is utilized within a programmable device to configure demultiplexers and multiplexers which map I/O address control line signals to set up various communication paths for address I/O exchanges. I/O configuration is entirely removed from add-on cards through the use of the programmable device. Accordingly, such add-on cards only require minimum circuitry, thus facilitating the use of miniature or baby cards as option cards which are much smaller than standard add-on cards.

Apparatus for selecting a user programmable address for an I/O device

The present invention relates to a method and apparatus to provide a write only register that is implemented with a low cost device yet provides the means whereby the register may be read, glitch free, using a predetermined procedure.

Method and apparatus for reading data from a write only port

This invention relates to a system for providing programmable configuration protection of a programmable Input/Output device. By configuration protection, it is meant that the programming options of an I/O controller can be set in accordance to a given environment, and then by use of a programming controlled signal, prevent the changing of the programmed environment or remove those programmed options considered unsafe in the now secured environment.

Method and apparatus for preventing unauthorized access to peripheral

A control circuit which allows computer systems to modify signal timing relationships in the hardware via programmable ports in the system, thereby allowing timing adjustments to be made without effecting motherboard hardware. The control circuit includes a plurality of delay devices configured to provide a plurality of delays under program control. The control circuit is adapted to extend the duration of a write signal to enable data to be latched, normally on the trailing edge of the write signal to avoid latching invalid data.

Growing community of inventors

Saint Joseph, MI, United States of America

Terence Paul O'Brien