Browse Prior Art Database

Translator for Virtual Segment Addresses

IP.com Disclosure Number: IPCOM000083620D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Smith, HF: AUTHOR

Abstract

The translator includes an addressing arrangement allowing virtual memory addressing and incorporating swapping of variable-length segments comprising various numbers of fixed-length blocks. The virtual address 10 includes a segment number 11 and an offset 12. The segment number is added to a constant 13 and used to address a double-entry segment table 14. If the segment is in main memory, the addressed position of the table indicates the main memory block which is the starting point for the segment. and indicates the segment size. If the segment is not in main memory, the table indicates a flag value, raising a branch condition 15 so that system software can obtain the data.

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Translator for Virtual Segment Addresses

The translator includes an addressing arrangement allowing virtual memory addressing and incorporating swapping of variable-length segments comprising various numbers of fixed-length blocks. The virtual address 10 includes a segment number 11 and an offset 12. The segment number is added to a constant 13 and used to address a double-entry segment table 14. If the segment is in main memory, the addressed position of the table indicates the main memory block which is the starting point for the segment. and indicates the segment size. If the segment is not in main memory, the table indicates a flag value, raising a branch condition 15 so that system software can obtain the data.

In the former case, the block number is combined with the offset portion in an "overlap" adder 16 to produce a real address. The offset portion of the address is also supplied to a comparator 17 for comparison to the segment size value from the segment table 14. If the offset is greater than the segment size, another branch condition 18 is raised to allow the system software to take control.

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