| 摘要 |
PURPOSE:To expand the number of addresses 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 a spcific ROM. CONSTITUTION:An 8K bytes memory element having address ports more than the number of address lines L0-L11 applied from the CPU1 to the ROM3 by one is used as the ROM3 and 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 an 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 can be expanded and the capacity of the memory and the capacity of the program also can be expanded by using the specific memory element and the specific address signal and switching the address area of the ROM. |
