| 摘要 |
<p>PURPOSE:To facilitate the development of a program and to execute a test which does not depend on a user ROM by constituting a character ROM of a ROM where rewriting is possible and a mask ROM and selecting either of ROMs by a ROM area selection circuit. CONSTITUTION:The character ROM 5 has the ROM area 5a where rewriting is possible and the mask ROM area 5b in which the polarity of one bit is set different among the bits where the addresses of one part of the address for one character are adjacent. Then, a ROM area selection signal generation means 8 for selecting either of the areas of the ROMs and the ROM area selection circuit 7 which receives the selection signal of the means 8 and selects either the ROM area 5a where rewriting is possible or the mask ROM area 5b are provided. Thus, the development of the program by a user is facilitated and the test in the case of incorporating the ROM where rewriting is possible is facilitated.</p> |
