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Chapter 4. System AHachment
This chapter contains information about the controller-to-host end of the
communications path.
Local Attachment
Locally, a controller is attached to a System/370-type processor through a selector,
multiplexer, or block multiplexer channel. The controller is attached by cables to
one of the controller positions on the host channel interface. From the host
computer, the channel provides the controller with both the data for display and
printing, and the control information it needs to direct the operation of its attached
terminals. In their buffer storage, the terminals store the data from the controller
for display or printing. Each display station's buffer permits simultaneous
presentation of the display image and composition of a message from the
keyboard.
Locally attached controllers can be positioned as far as 122 meters (400 feet) from
the system channel, depending upon the system and channel configuration.
Locally attached controllers are the models 1 Land 11 L. These models also attach
to the IBM 3044 Fiber Optic Channel Extender Link, permitting the controllers to be
placed up to 2 kilometers (6600 feet) from the channel.
Remote Attachment
Remotely, the controller and the system channel can communicate in two ways: (1)
through a channel-attached communication controller or an integrated
communication adapter using BSC protocol, or (2) through a communication
controller using BSC or SDLC protocol. The controller communicates with
intermediary devices by means of communication facilities (data links), such as:
• Modems
• Voice-grade channels
• Equivalent facilities such as telephone lines, microwaves, or satellites.
The following controllers can be remotely attached using BSC protocol:
• 3174 Models 1R, 11R, 51R, 61R, 81R, and 91R.
These controllers can be remotely attached using SDLC or X.25 protocols:
• 3174 Models 1R, 11R, 2R, 12R, 51R, 61R, 52R, 62R, 81R, 91R, 82R, and 92R.
Chapter 4. System Attachment
4-1
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