This invention relates to data selection and data storage apparatus and more particularly to a simplified circuit which uses a pair of cross-coupled transistors, a plurality of current switches and a current source to select and store data from a plurality of data signals. Gating signals applied to the current switches determine which data signals are selected for storage in the apparatus.
Data selectors are used in high-speed data processing systems to control the flow of information to various portions of the processing system such as the storage registers. In prior art data processing systems a plurality of data selectors are connected to the storage registers so that data from a plurality of the data sources may be stored in the storage register. Each of the data selectors in the prior art system includes gates which are connected to the input leads of the storage register. The storage register includes a plurality of separate latches or flip-flops. The data selectors and the latches each use a separate current source and use separate controls each of which require gates, power and area on integrated circuit chips. The present invention alleviates the disadvantages of the prior art data selectors and storage registers by combining the functions of these selectors and registers into a single circuit. This combination reduces the power dissipation, reduces the number of gates required, reduces the area required on integrated circuit chips and decreases the cost.
It is, therefore, an object of this invention to provide a new and improved selector latch gate which incorporates the functions of both the data selector and the storage register.
Another advantage of this invention is to provide a selector latch gate having reduced power dissipation.
A further object of this invention is to provide a selector latch gate which develops both true and complementary output logic signals.
A further object of this invention is to provide a selector latch gate which stores the true or complement of data input signals.