| 摘要 |
<p>PURPOSE:To suppress the increase of the number of output terminals of an LSI, by outputting plural data signals, which are selected from many kinds of data signals, as one group from the same terminal. CONSTITUTION:Auxiliary input signals applied to a data bus 1 and a terminal 5 are always inputted to a decoder 6. Multiplexers 7 and 71 are attached to output ports 43 and 44, respectively. Bus data or the output of the decoder is selected by a switching control signal from a gate circuit 8. Outputs of multiplexers 7 and 71 are inputted to latches 33 and 34 and are taken out output ports 43 and 44 by the latch control. Thus, output ports are used in two ways. In one way, they are used as output ports independent of each other, and the contents of the data bus are outputted as they are. In the other, two output ports are used as one output port, and the decoder is used to convert 4-bit data to 8-bit data, and this data is outputted at a time, and thus, output ports are used as an 8-bit output port.</p> |
