| 摘要 |
<p>PURPOSE:To reduce power consumption by supplying electric power only to a ROM for reading out a program or data and interrupting power supply to other ROMs. CONSTITUTION:When a program or data is to be read out from a ROM8, a ROM selecting data 11 is inputted to a buffer 2 and the output of the buffer 2 is supplied to a decoder 3. When the output of the decoder 3 to a driver 4 is in the low level, the output is inverted by the driver 4, the bases of TRs 6a-6c are turned to the high level and current is made to flow from a power supply circuit 1 to the TRs 6a-6c through resistors 5a-5c to drive the TRs 6a-6c. Consequently, base current is made to flow into TRs 7a-7c to turn on the TRs 7a- 7c and electric power is supplied to the Vcc terminal of the ROM. When the output of the decoder 3 is in the high level, the output is inverted by the driver 4 and turned to the low level, so that the TRs 6a-6c are turned off and the TRs 7a-7c are also turned off. Thus, electric power is not supplied to the Vcc terminal of the ROM.</p> |
