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1.70/668-11,21,
31 COMMUNI-
CATION
CONTROLLER-
MULTICHANNEL
(CCM)
GENERAL
DESCRIPTION
• The Communication Controller-Multichannel (CCM) peripheral device
multiplexes and controls the transmission of data to and from various re-
mote terminals and systems. Figure
1-1
shows the physical location of the
CCM with respect to the processor, communication line buffers, common
carrier interface devices, and the remote
I/o
terminals.
The CCM is a multiplexing device capable of providing a distinct level
of data and system control when used with the 70/35, 70/45, or 70/55 Pro-
cessors o A single multiplexor trunk connects this device to its controlling
processor.
The CCM is capable of servicing a mixture of buffers with a
total data rate transfer of 6,000 bytes per second.
A maximum of seven CCMs can be attached to the 70/35 Processor while
the 70/45 and 70/55 Processors can accommodate up to eight CCMs. The
actual number of CCMs used, however, is governed by the size of the pro-
cessor memory, the number and data rates of the communication lines
serviced by the CCMs, and the demands of other peripheral devices con-
trolled by the processor.
There are three different models of CCMs. The CCM Model 70/668-11
has a maximum control capacity for 16 communication lines; the CCM
Models 70/668-21 and 31 have a maximum control capacity of 32 and 48
lines respectivelyo The CCM services each communication line through a
single buffer based upon the type of remote terminal or system with which
it must operate. Two buffers are required for the termination of full duplex
communication facilities.
Each buffer is deSignated by a specific device
address.
Utilizing the maximum number of CCMs per processor, a 70/35 Pro-
cessor can simultaneously control and service 176 communication lines.
Theoretically, the 70/45 and 70/55 Processors can control 240 com-
munication lines
o
The actual limits of communication line servicing and
control are dependent upon the types and data rates of the circuits involved
as well as the memory size of the processor
0
A maximum of 16 different
combinations of various remote terminals and communication line char-
acteristics can be accommodated in a single CCM. In some instances the
size of the individual buffers, and the particular combinations of these
buffers, may cause physical limitations which result in systems where a
CCM cannot physically service the number of buffers given as a theoretical
maximum.
Although the maximum continuous CCM throughput is 6KB, the CCM can
maintain a byte transfer rate to the processor of 50KB for a maximum of
60 consecutive byte transfers. This rate would be realized if all 20 lines
covered by a single buffer scan cycle each produced a completely framed
character for transfer to the processor .and each of these characters re-
quired the generation of a two- byte coordination messageo
1-1
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