| 摘要 |
<p>PURPOSE:To improve the efficiency of product development by constituting a subroutine or the like fixed at the stage of development with mask ROMs in advance and constituting a subroutine or the like being subject to change by means of EPROMs so as to attain products without using mask ROMs for all of components. CONSTITUTION:A single chip microcomputer is formed by a CPU1, an RAM2, a decoder 3, a mask ROM4, an EPROM5, a decoder 6, an I/O interface 7 and a clock generating circuit 11. Then fixed subroutines or the like having actual results are stored in the mask ROM4, and a main routine and subroutines subject to change are written in the EPROM5. The mask ROM4 and the EPROM5 are provided as the ROMs and they are accessed by one decoder 6. Thus, the CPU1 does not recognize the individual mask ROM and EPROM but recognizes them as one ROM.</p> |
