Browse Prior Art Database

Advanced Processor Clock Skew Card for the RT-PC

IP.com Disclosure Number: IPCOM000036097D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 4 page(s) / 95K

Publishing Venue

IBM

Related People

Franz, KW: AUTHOR

Abstract

The Advanced Processor Clock Skew Card verifies proper operation at the extremes of the manufacturing process of the processor complex and clock generator modules.

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Advanced Processor Clock Skew Card for the RT-PC

The Advanced Processor Clock Skew Card verifies proper operation at the extremes of the manufacturing process of the processor complex and clock generator modules.

When testing complex processor cards, it is difficult to verify proper operation of the processor and clock generator modules at the extremes of the manufacturing process. The internal timings and other

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electrical characteristics of a module may vary significantly depending on the variations in the manufacturing process. A combination of these variations, particularly in the area of timing, may cause machine failures which may not be detected by simulation or by testing a small sample.

The Advanced Processor Clock Skew Card was designed to simulate the operation of the modules at the extremes of the manufacturing process. It provides the capability to vary the system clock timing parameters. The Clock Skew Card is fully programmable from a PC. Two additional cards are used to interface to the Clock Skew Card (Control

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Card and PC interface card). The Clock Skew Card provides the following features: delays clocks; delays leading and trailing edges of clocks; varies pulse widths; and the capability of skewing nine different clocks, one at a time. The software for the Clock Skew Card provides the following additional features: menu driven operation; trial selection and settings; capability of running unattended; time delay start; multiloop capability; optional feedback loop to indicate test case completion; and time stamping.

The clock skew card has seven major functions for changing clock waveforms. (Fig. 2). The first function is the skew clock generator which is used for generating the clock on the Clock Skew Card. The second function is the multiplexer which selects between nominal and skewed clocks. The multiplexer is controlled by the start/stop and glitch control logic. The third function is the start/stop control logic which determines when the system has started or stopped. The fourth function is the glitch control which prevents glitches on the clocks during the time when the address to the multiplexer is changing. The last three functions work together to provide delayed clocks, or clocks with leading and trailing edges changed from nominal (type of operation) for the multiplexer. The resolution of these three functions is one nanosecond.

The clock timings are changed to the process...