Motorola 700/800-Series User Manual

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Hardware Preparation and Installation
2
System Considerations
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 
ProgrammerÕs 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 
ProgrammerÕs 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.