Bulletin number: 64
Products affected: D700D
Description: Differences between communication on hard and soft channels.
Component: THE DOCUMENTATION
Date: Tue May 15 17:00:00 GMT 1990
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Section 5.11.1 

Add an extra paragraph:

The strict rules of occam protocol require the two processes involved
in a communication to agree on the lengths of the blocks communicated and
use of strict channel protocols will ensure this. It is also possible to
use anarchic protocols (   CHAN OF ANY ) to avoid these compiler checks.
The behaviour of communications where the sender and receiver have different
expectations of the block length differs on the transputer between hard
channel (transputer links) and soft (internal) channels. On hard channels
each byte is acknowledged individually and so it is only necessary for the
total number of bytes received to match the number sent. On soft channels
each block is an acknowledged
unit of communication and the size actually communicated will be that required
by the second of the two processes to become ready.
In occam the lengths of blocks are determined by the types of the
expressions sent and variables used as destinations. Users of anarchic
protocols need to be aware of these differences if a program is adapted
from hard to soft channels or vice-versa. Anarchic ptotocols should be
avoided whenever possible.