| 摘要 |
A microcomputer includes a main memory system which is accessed, substantially independantly, by the CPU and a subsystem, for example a video display subsystem. The memory system comprises a base memory and an optical add on expansion memory. When only the base memory is installed, consecutive locations have consecutively numbered addresses, and both the CPU and subsystem access individual locations. When both memories are installed, one has even numbered addresses and the other odd numbered addresses. With both memories installed, the CPU still accesses individual locations, but the subsystem addresses even addresses to obtain, for each access, data from the even address and the next higher odd address, thereby accessing a location in both memories. Thus the memory bandwidth for the subsystem is effectively doubled when the expansion memory is installed. |
