| 摘要 |
<p>The apparatus receives incoming items of data (e.g. full memory addresses) from a primary data processing unit, converts these to relatively short identifiers for a secondary unit, and reconverts when the identifiers are returned by the secondary unit. An identifer memory 12 holds the set of identifiers 0 to (n-1), and a counter 10 and decrement by 1 circuit 11 point to the bottom location (R) of a list of unassigned identifiers and the next location down (W). An incoming item of data is assigned the identifier in location R, and written in the location in a data memory 13 addressed by the resulting identifier, and the counter is incremented by 1. The identifier can then be used to retrieve the item of data. To delete an identifier on termination of the associated transaction, it is written into the location W, and the counter is decremented by 1. A fresh incoming item of data can be assigned an identifier simultaneously with the deletion of an identifier and the retrieval of its associated item of data. An overflow signal from the counter indicates when the system has all identifiers in use and can accept no more items of data.</p> |
