IBM Series 1 User Manual page 12

c
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A variety of interfaces are provided for the user to attach
his own input/output (I/O) devices and instruments to an IBM
4953 or 4955 Processor. Both serial and parallel data paths
are provided in addition to a multifunction timer. The user
may
choose one of the I/O adapter features or design his own
I/O
adapter to communicate directly with the processor I/O
channel.
Fiqure
1-1
shows the various methods of attachment and
the available attachment features. Each attachment is
described in subsequent sections cf this chapter.
PROCESSOR I/O CHANNEL
Input/output devices are attached to the ~rocessor through
the I/O
channel. The channel directs
the
flow of
information between the I/O devices and main storage. It
contains the facilities for the control of the I/O
operations and can accommodate 256 device addresses. The
I/O channel is asynchronous with lultidropped lines that
link the prccessor resource to its external facilities. The
I/O channel architecture includes: address, control, and
data siqnal lines.
To use the full capability
of
the channel including
cycle steal, the user can connect to the I/O channel lines
usinq any of the following features:
• c ha nne
1 re power fea t
ure
• channel socket adapter feature
These features are described in the following sections.
The channel repower feature is a
channel that repovers and isolates
This feature permits connection of
or controllers via four connectors
circuit ca rd.
serial feature on the
the channel signal lines.
additional I/O adapters
on the top of the repower
Introduction 1-1