Illegal Access To Ip Modules From External Vmebus Masters - Motorola MVME162FX Programmer's Reference Manual

Board Description and Memory Maps
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Illegal Access to IP Modules from External VMEbus Masters

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which start onboard and then access off-board resources. The
MVME162FX does not fully support all RMW operations in all
possible cases.
The MVME162FX makes the following assumptions and supports
a limited subset of RMW instructions. The MVME162FX supports
single-address RMW cycles caused by TAS and CAS instructions.
Because it is not possible to tell if the MC68040 is executing a single-
or multiple-address read-modify-write cycle, software should only
execute single-address RMW instructions. Multiple-address RMW
cycles caused by CAS or CAS2 instructions are not guaranteed
indivisible and may cause illegal VMEbus cycles. Lock cycles
caused by MMU table walks do not cause illegal VMEbus cycles,
and they are not guaranteed indivisible.
When a device other than the local MVME162FX is operating as
VMEbus master, access by that device to the local IP modules is
subject to restrictions.
Access to the IndustryPack memory space is supported in all cases.
As a result of the difference in data width between the VMEbus and
the IP modules (D32 versus D16), however, access to the
IndustryPack I/O, ID, and Interrupt Acknowledge space is not
supported for single IP modules. This applies to IndustryPacks a, b,
c, and d.