GE 235 System Manual page 24

PERIPHERAL SWITCH CONTROL UNIT
The Peripheral Switch Control Unit is an optional feature that makes possible the switching of a s
many a s seven 1 / 0 device controllers between two GE-200 Series systems. Any I/O device
normally connected to one of the numbered priority control channels may be switched by this unit.
This switching capability permits optimum utilization of all peripheral equipment for multiple
system operation.
The heart of the unit i s the switch control console (see the accompanying illustration). The
console i s connected to each 1/O device to be switched and to the two central processors. The
console performs two functions: 1) assigns each controller to the desired central processor
and 2) assigns the selected priority to each 1 / 0 device.
Two lighted pushbuttons a r e associated with each 1/0 device--one on the left of the panel
(SYSTEM 1
-
SELECT PERIPHERAL) and one on the right (SYSTEM 2
-
SELECT PERIPHERAL).
Separating each pair of SELECT buttons is a r o w of ADDRESS SELECTION buttons for determining
the priority level of the associated 1 / 0 device. Additional circuitry actuates one of the ADDRESS
SELECT ERROR indicators if more than one controller is switched to the s a m e priority level on
one system. A vertical column of eight numbered panel indicators marked SELECTED ADDRESS
a l s o appears on each side of the panel.
These indicators show which priority levels a r e in use
on each system.
1/0 DEVICE SWITCH CONTROL UNIT CONSOLE PANEL