| 摘要 |
<p>A memory expansion scheme (90) is provided which permits a program to automatically cross memory bank boundaries, without user intervention. A memory bank address register (94) stores a value corresponding to a selected memory bank (i.e. Bank 0), in a 4-bit subfield (K-Field). In the preferred embodiment, the K-Field is implemented using six (6) bank number registers, each of which is coupled to the corresponding address register, (92) to form a 20-bit (extended) logical address. During an effective address calculation, in the index addressing mode, a 16-bit logical offset address, stored in an offset register, (96) is added to the 20-bit (extended) logical address, by an adder (98) in the ALU. (69) The adder (98) transfers a 20-bit physical address onto an address bus, (44) via an address buffer. (56) When the calculated address crosses a memory bank boundary, the upper four (4) address bits (A16-A19) are automatically updated, thereby enabling the program to cross a memory bank boundary without user intervention. <IMAGE></p> |
