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Browse Prior Art Database

Versabus Module Eurocard Bus Auto Slot Identification

IP.com Disclosure Number: IPCOM000113391D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Betcher, CW: AUTHOR [+3]

Abstract

A logic circuit is disclosed which allows the Versabus Module Eurocard (VME) bus slot ID to be automatically assigned immediately after power on reset (POR). The circuit utilizes several of the VME bus arbitration control signals and a subset of the VME address bus to implement the function.

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

Versabus Module Eurocard Bus Auto Slot Identification

      A logic circuit is disclosed which allows the Versabus Module
Eurocard (VME) bus slot ID to be automatically assigned immediately
after power on reset (POR).  The circuit utilizes several of the VME
bus arbitration control signals and a subset of the VME address bus
to implement the function.

1.  Upon power up, all VME cards which require slot ID initialization
    shall drive *BR3 active ("*" indicates an active low signal).  On
    the slot 1 (arbiter) CPU, a five bit counter, CTO (slot ID
    counter), contains the binary slot ID of the next card to be
    initialized.  This counter is set to a count of two by POR.

2.  After POR goes inactive, the slot 1 CPU arbiter ARBO detects *BR3
    active, and drives *BG3OUT active in accordance with the normal
    VME bus arbitration protocol.

3.  The next VME card downstream ("VME card X") from slot 1 requiring
    slot ID initialization detects *BG3IN active.  The leading edge
    of *BG3IN sets DFFO in the slot id logic for VME card X.  Note
    that devices not requiring slot ID should simply pass through
    *BG3IN as is.

4.  A single pulse of approximately 100ns is generated on *BBSY by
    slot ID logic on VME card X (from logic elements DF1-3, GT2-3).
    The leading edge of *BBSY causes the arbiter ARBO to disable
    *BG3OUT.  The trailing edge of *BBSY loads the value from the
    slot ID counter CTO into the slot ID register RGO of VME card X.
    Note that the...