Address control of memories in microcomputer systems - uses PROM modules to control memory module selection and data bus transfers

摘要

The address control for a microcomputer system allows selection of a large number of memory modules. A programmable read only memory (PROM1) contains coded values indicating the specific memory modules (SP1-SPn) used in the system. Address bits (Ah,Am) access the PROM to provide an output that is decoded (DEC) to generate specific enable signals (E) that act as a chip select. A separate programmable read only memory (PROM2) responds to instruction bits to control tri-state drivers (TR) to control data flow to and from the data bus (DBE).