Data Bus Structure; Local Bus Arbitration; Mc68040 Mpu - Motorola MVME167 Series Installation Manual

Board Level Hardware Description

Data Bus Structure

2

Local Bus Arbitration

MC68040 MPU

2-12
The local data bus on the MVME167 is a 32-bit synchronous bus
that is based on the MC68040 bus, and supports burst transfers and
snooping.
The various local bus master and slave devices use the local bus to
communicate.
The local bus is arbitrated by priority type arbiter and the priority
of the local bus masters from highest to lowest is:
1. 82596CA LAN (highest)
2. CD2401 serial (through the PCCchip2)
3. 53C710 SCSI
4. VMEbus
5. MPU (lowest)
In general, any master can access any slave; however, not all
combinations pass the Òcommon sense testÓ. Refer to the Single
Board Computers Programmer's Reference Guide and to the user's
guide for each device to determine its port size, data bus
connection, and any restrictions that apply when accessing the
device.
The MC68040 processor is used on the MVME167. The MC68040
has onchip instruction and data caches and a floating point
processor. Refer to the M68040 user's manual for more information.