Data Transfer; Computer Interface Unit (Ciu 931) - GE DATANET-30 System Manual

Data Transfer
The PIU connects to the memory interrupt interface and is normally assigned interrupt cycle
two. Only one interrupt cycle may be assigned to the PIU. This allows a transfer rate of 28,000
DATANET-30 words per second.
Data is transferred in both directions, but only in one direction at a time. Control of the direction
of data transfer is established by either DATANET-30 on a receive only basis.
The PIU does not allow a program to initiate transmission. The DATANET-30 which is to receive
data must initiate the data transfer. This method of operation protects the memory in one
DATANET-30 from being destroyed by mistake by the other DATANET-30 program.
CONTROLS AND INDICATORS. All controls and indicators are by program only, except for manual
reset on the control panel.
COMPUTER INTERFACE UNIT {CIU 931)
The CIU 931 Computer Interface Unit provides the means for connecting the DATANET-30 and
a GE-400 or -600 Series computer (Figure 22).
The computer interface unit (CIU) connects into the buffer selector of the DATANET-30 and into
one standard input/output channel of the other computer. The buffer selector address of the CIU
is specified by the buff er selector address channel for the CIU. Since the CIU connects the
DATANET-30 with either a GE-400 or -600 Series computer, for the purposes here, both of these
computers will be ref erred to as the "external computer." More than one CIU can be installed in
a DATANET-30. Each CIU occupies two modules. There is no restriction on the number used,
other than the physical space occupied.
GE-600
GE-400
DATANET-30
CIU 931
CIU 931
Remote Terminals
Figure 22. CIU 931 Connecting a DATANET-30 with an External Computer
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