Data Channel - IBM 709 General Information Manual

The multiplexor handles as many as eight input-
output data channels. The data word is handled in
the normal fashion of 36 bits in parallel, coming from
or going to core storage.
Data Channel
The
IBM
7607 Data Channel (Figure 77) is another
new unit used with the 7090 system. Data channels
replace the data synchronizers and tape controls used
with the 709 system.
Each data channel is basically a completely separate
and independent input-output channel. It provides
for the transmission of data between the input-output
device and core storage, a transmission that is inde-
pendent of computing. As in the 709 system, the
stored program starts an input operation by defining
which input device is to transmit and which core
storage area is to receive. The stored program can
then proceed to execute instructions (compute) not
related to the input transmission. When a full word
has been assembled in the data channel, this word is
put into core storage. An interruption of the compute
program could occur only during the execution of a
convert or, in rare cases, some floating point instruc-
tions. This interruption could be only for 2.18 micro-
seconds. This procedure is reversed if an output oper-
ation is being performed.
Thus, one or more data channels can be occupied
with an input operation while others are being used
STORAGE
Figure 78. Data Channel and
CPU
Processing,
IBM
7090
36 IBM 709·7090
Figure 77.
IBM
7607 Data Channel
for output purposes. All operations are simultaneous
with the processing that is occurring in the central
processing unit.