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Method and Apparatus to Attach Devices Implementing a Motorola MPC860 External Bus Interface to the IBM CoreConnect Processor Local Bus

IP.com Disclosure Number: IPCOM000014467D
Original Publication Date: 2000-Nov-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue

IBM

Abstract

Method and Apparatus to Attach Devices Implementing a Motorola MPC860 External Bus Interface to the IBM CoreConnect Processor Local Bus The disclosed device is a bridge between the *IBM CoreConnect PLB bus and an on-chip implementation of the **Motorola MPC860 bus. The disclosed device enables reuse of existing Motorola MPC860 bus devices with minimal modification. This bus bridge provides savings in engineering costs. The MPC860 bus to which the disclosed bridge is attached is not a true external bus. It is an on chip implementation of the MPC860 external bus. Because this bus is implemented on chip, and is intended to be implemented in an IBM *BlueLogic technology, none of the MPC860 bus signals may enter a high impedance state. For this reason, when MPC860 bus control lines are not in use, they must always be driven to their inactive state. Other than this, the on chip MPC860 bus is logically consistent with the Motorola MPC860 external processor bus. For simplicity, this document will refer to the on chip MPC860 bus as the "EMBUS", and will refer to the disclosed device as the "PLB to EMBUS bridge" or simply the "bridge."