| 摘要 |
<p>The invention relates to circuits comprising on the same chip both a microprocessor and an internal read-only memory of programs. In order to facilitate debuggings of the programs of the read-only memory without fabricating, in light of the debugging, a special version of the circuit which is too different from the final version, it is proposed according to the invention to use an external memory for debugging. A contact point PS1 on the chip serves to transmit, in serial mode, a program originating from an external memory MX. A contact point PS2 for mode selection makes it possible to define if the microprocessor is to work in internal ROM mode (normal mode) or in external ROM mode (debugging mode). The circuit elements added to permit this double operation are of limited size, so that it is possible to use a final circuit version identical to the provisional debugging version, with the exception of the fact that the final version contains a final program in read-only memory. In general the contents of the read-only memory are defined by only one mask, and consequently only one different mask will have to be produced for the final version. <IMAGE></p> |
