Method of monitoring the bring up of all units in a multiple system from a remote unit including diagnostic testing with visual indicator illumination indicating operability

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Although the present invention, to be described hereinafter, can be adapted for use in any type of computer system, it works well in a computing system adapted for use in a retail establishment, department store, etc.
, and as such will be described in that environment.
Such special purpose computing systems are hereinafter referred to as point of sale terminal systems.
However, this should not be construed as a limitation on the scope of the present invention since it is well within the skill of one skilled in the art to adjust the invention to work with any computing system.
FIG.
1 shows a block diagram for a point of sale computing system.
The system includes a plurality of terminals identified by numeral 10 and coupled through a communications medium 12 to a store controller 14.
The store controller is coupled through a communication link 16 to a host computer (not shown).
As can be seen from the figure, the communications medium is configured into a loop.
Messages on the loop flow in a unidirection identified by the arrow.
In this type of configuration the terminals are used to tally sales transactions while the store controller performs data collection functions, price files and store management functions.
FIG.
2 shows a block diagram of the components which can be located in terminal 10.
The components include a second order control unit identified by numeral 18 and a plurality of I/O devices identified by numerals 20, 22, 23, etc.
The I/O devices are connected by a serial I/O channel 26 to the second order control unit 18.
Each of the I/O devices 20-23 is coupled over respective conductors to the serial I/O channel 26.
Similarly, a conductor identified by numeral 28 interconnects a first order control unit 30 to the second order control unit 18.
Although not shown, a similar set of I/O devices (20-23) is connected to the first order control unit 30.
The cables or conductors supply both power and control signals from the control units to the I/O devices