| 摘要 |
A simple and inexpensive digital circuit is employed for selectively assigning television channels to be output to a plurality of small auxiliary television monitors and a main television monitor. Each of the television monitors is digitally tuneable. After the original channel numbers are selected by the user for display on the main monitor and on each of the auxiliary monitors, the user may designate a new channel to be displayed on the main monitor. The new channel may be one of the channels presently being viewed on one of the auxiliary monitors or may be one of the channels which is not yet displayed. In the case where the channel to be displayed on the main monitor is then being displayed on one of the auxiliary monitors, the circuit interchanges the channel displayed on the main monitor with that on the auxiliary monitor. In the case where the new channel is not displayed on any of the monitors, the new channel is displayed on the main monitor and the channel previously displayed on the main monitor is switched to one of the auxiliary monitors with the channel previously displayed on that auxiliary monitor being deleted. These switching functions are accomplished by a ring shift register in which the channel numbers of each of the auxiliary monitors are stored and manipulated. The new channel designated by the user as well as the old channel which was previously displayed on the main monitor are placed in corresponding registers which form a parallel chain with each other and one of the shift registers and the ring shifter. Control of sequencing is determined by a plurality of status flip-flops and by firmware control.
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