| 摘要 |
PURPOSE:To expand the number of addresses of a ROM and the capacity of a program by using a memory element having address ports more than the number of address lines applied from a CPU to the ROM connected to the CPU. CONSTITUTION:Since an 8K bytes memory element having 13 address ports A'0-A'12 more than the number of address lines L1-L11 applied from the CPU1 to the ROM3 by one is used for the ROM3, the number of addresses is twice the ordinary number of addresses. Namely, the address area of the ROM3 is divided into ''0'' and ''1'' pages; when the signal ''0'' is inputted to the address port A'12, the ''0'' page is selected, and in case of the input of a signal ''1'', the ''1'' page is selected. Thus, the number of addresses and the capacity of the program can be expanded by using the memory element having address ports more than the number of address lines applied from the CPU to the ROM3. |
