Introduction; Channel Interface - IBM 3704 Reference Manual

Introduction
Channel Interface
The IBM 3704 and 3705 Communications Controllers are transmission control
units with a resident control program. Because of the many variations that can be
obtained with different programs, the information contained in this manual is
valid only when using the IBM-supplied Emulation Program or Network Control
Program. Alteration of these programs can affect these specifications.
The IBM 3704 and 3705 provide for the connection and control between a variety
of local or remote input/ output devices and a system processor. A control
program, residing in the IBM 3704 and 3705, performs many of the functions
previously performed by the transmission control unit hardware.
For a description of the IBM 3704 and 3705 hardware and program capabilities,
refer to Introduction to the IBM 3704 and 3705 Communications Controllers,
GA27-3051.
Two types of channel adapters are available for the IBM 3705; only one type is
available for the 3704. The Type 1 Channel Adapter provides attachment to an
IBM System/360 or System/370 byte-multiplexer channel. The Type 2 Channel
Adapter (available only on the 3705) provides attachment to an IBM System/370
selector channel, byte-multiplexer channel, or block-multiplexer channel.
Channel Interface Signal Lines.
Except for 'select out' and 'select in', the maxi-
mum allowabie internal resistance (including all contact resistance) for every
signal line is less than 1.0 ohms. The combined 'select out' and 'select in' maxi-
mum resistance is less than 1.5 ohms. For a detailed description of the channel
interface, refer to IBM System/360 and System/370 Interface Channel to
Control Unit-Original Equipment Manufacturers' Information, GA22-6974.
Introduction I