| 摘要 |
<p>Address generating apparatus which uses narrow data paths for generating a wide logical address (20) and which also provides for programs to access very large shared data structures outside their normally available addressing range. Selective indexed addressing (10, 12, 14, 16, 23, 25) is employed for providing both index data (16b) and variable dimension override data (16c). During address generation, selected (14) index data (I S) is used in conjunction with a displacement (D) provided by an instruction (10) for determining an offset (20a). Dimension override data accompanying the selected index data is used to selectively (23) access an address locating entry (48) in a table (25) of entires corresponding to the applicable program. The resulting accessed address locating entry (48) is in turn used to determine the particular portion (20b) of memory (40) against which the offset (20a) is to be applied.</p> |
