Browse Prior Art Database

Elimination of Signal Recovery on TA_ on a System Bus Interface

IP.com Disclosure Number: IPCOM000112353D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 25K

Publishing Venue

IBM

Related People

Arroyo, RX: AUTHOR [+4]

Abstract

Disclosed is a method of eliminating the signal recovery (or precharge) of the TA_ (transfer acknowledge) signal on a system bus interface.

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Elimination of Signal Recovery on TA_ on a System Bus Interface

Disclosed is a method of eliminating the signal recovery (or
precharge) of the TA_ (transfer acknowledge) signal on a system bus
interface.

      The interface defines the transfer acknowledge signal (TA_), to
be used by slaves to indicate that a data transfer is complete.  The
problem with the signal is that, under the original definition, a
slave was not required to drive the signal until it was ready to
terminate the Therefore, the signal must have a pullup resistor on it
and the slave must recover (or precharge) the signal at the end of
the data tenure.  This is difficult to do because it must be a half
cycle action, and it is also cycle limiting:  At high frequencies,
the precharge pulse becomes too short to adequately charge the wire.

      The solution to the problem is to require slaves to drive TA_
immediately at the beginning of the data tenure.  The slave is not
required to drive it active, the only requirement is to drive it to a
known state (active or inactive).  In this way, each data tenure
begins correctly and the precharge is eliminated.