| 摘要 |
<p>A method of providing a communication circuit between a processor system and an external system (EB) by means of the signals normally used to a read-only storage, such as a ROM or EPROM. According to the invention the address bus (AB) of the processor system and the read control signal (RC) are used to generate the transmission data, the address bus (AB) utilizing selected addresses to form the transmission data in interaction with the CPU of the processor system, said addresses being transmitted from the processor system by the read control signal (RC) triggering a data port by means of an address control circuit (AMC). As a result, it is possible to perform a write operation by means of the existing signals for a read-only storage, such as a ROM or EPROM, thus utilizing that the mentioned ROM or EPROM is mounted on a socket, whereby it is possible to provide an extra communication circuit to an existing processor system.</p> |
