System Considerations - Motorola 700 Series Installation And Use Manual

Hardware Preparation and Installation

System Considerations

2
2-18
The 700/800-series MVME162LX draws power from both the P1
and the P2 connectors on the VMEbus backplane. P2 is also used for
the upper 16 bits of data in 32-bit transfers, and for the upper 8
address lines in extended addressing mode. The MVME162LX may
not operate properly without its main board connected to VMEbus
backplane connectors P1 and P2.
Whether the MVME162LX operates as VMEbus master or as
VMEbus slave, it is configured for 32 bits of address and 32 bits of
data (A32/D32). However, it handles A16 or A24 devices in the
address ranges indicated in Chapter 3. D8 and/or D16 devices in
the system must be handled by the MC68040 software. Refer to the
memory maps in the MVME162LX Embedded Controller
Programmer's Reference Guide.
The MVME162LX contains shared onboard DRAM whose base
address is software-selectable. Both the onboard processor and
offboard VMEbus devices see this local DRAM at base physical
address $00000000, as programmed by the MVME162Bug
firmware. This may be changed via software to any other base
address. Refer to the MVME162LX Embedded Controller
Programmer's Reference Guide for more information.
If the MVME162LX tries to access offboard resources in a
nonexistent location and is not system controller, and if the system
does not have a global bus timeout, the MVME162LX waits forever
for the VMEbus cycle to complete. This will cause the system to lock
up. There is only one situation in which the system might lack this
global bus timeout: when the MVME162LX is not the system
controller and there is no global bus timeout elsewhere in the
system.
Multiple MVME162LXs may be installed in a single VME chassis. In
general, hardware multiprocessor features are supported.