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CCM Device
Addresses
Coordination
Message Line (CML)
eeM
•
A list of suggested rules for implementing the assignment of device
addresses for processor systems utilizing CCMs is as follows:
10
All device addresses used by CCMs must start in an upward
sequence beginning at a number divisible by 16 (16 to 255). The
first 16 device addresses on a system must not be assigned to
communication lines but may be assigned to peripherals and CCM
common device addresseS:--
It
should be remembered, however,
that address (00)16 should always be usedfor the console typewriter.
2.
The identification for device address 255 is (FF) 6. Because this
could create confusion with the error indication wlfien coordination
messages are generated for this device address, it is not advisable
to assign it to an active line.
3.
The CCM line (buffer) scan can be reset at any pointo
It
is advis-
able to consider this in those cases where the numper of lines
serviced by a CCM is less than the total line servicing capacity
of that device. By doing this the CCM eliminates the unused buffer
scan positions from its scan cycle.
4.
If
multiple CCMs are attached to a system, peripheral device address
assignments should not be made between the first device address of
the first CCM and the last device address of the last CCMo
5. Device address assignments within a CCM servicing sequence should
be contiguous.
If
not contiguous, a dummy line status word must be
recorded in memory for each device address not usedo
6. In systems involving multiple CCMs, the high- speed communication
lines should be concentrated into one CCM, if possible, and this
CCM should be assigned a higher priority multiplexor trunk so that
it would be serviced before the other CCMs which control lower
speed lines.
Refer to the 70/35, 45, 55 Processor Reference
Manual (No. 70-35-601) as to the servicing of multiplexer channels.
7.
Common device address assignments for CCMs on multiple CCM
systems need not be contiguous or restricted to any specific
sequence.
However, such assignments must be outside the range
of device addresses assigned to communication buffers.
•
In order to provide for Processor-CCM coordination and initializa-
tion, a device address is used for control of each CCM. Assignment of
this 'common' device address is independent of the buffer device address
assignments and may be selected from any unused address outside the
address range assigned to buffers.
Command chaining is not permitted
in connection with the CML.
.
1-5
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