Bulletin number:  25
Products affected: Z999
Description: block move instructions
Component:
Date: Thu Mar 8 18:02:49 GMT 1990
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This replaces bulletin number 18.

If the block move instructions are used to move data between memory
and some memory-mapped device strange side effects can occur. If the
process carrying out the block move is descheduled in the middle of
the block move instruction it will subsequently restart at the
previous word boundary.  So re-writing/re-reading the memory-mapped
device. This will never matter during memory to memory transfers as
locations are simply re-read/overwritten.  A workaround is to use a
local PRI PAR around the block move to ensure that it is not
descheduled in mid transfer.

*** STOP PRESS *** STOP PRESS *** STOP PRESS *** STOP PRESS ***

The scoop from Dave '3d blk mv' Auld is :-

This is only the case if the source and destination are not identically byte
aligned (2 ls bits on T4/8s the same, 1 ls bit on T2).

If you are copying words from a 32 bit FIFO register, be sure that
you are writing on word boundaries to memory, and this will not be a
problem.