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Method for providing virtual addressing for externally specified addressed input/output operations

  • US 4,155,119 A
  • Filed: 09/21/1977
  • Issued: 05/15/1979
  • Est. Priority Date: 09/21/1977
  • Status: Expired due to Term
First Claim
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1. In a digital computer system of the type having a memory addressed by a real address, having a virtual addressing system for converting virtual addresses into real addresses utilizing a channel page table having a predetermined starting address, having input/output operations, having said input/output channels capable of externally specifying an address, and having channel state information which specifies a starting address of said channel page table, an improved method of addressing comprising the steps of:

  • treating said externally specified address as a virtual address having a page portion and a displacement portion;

    addressing said channel page table using said starting address of said channel page table;

    indexing into said channel page table with said page portion to select a particular location within said channel page table in order to obtain a page frame number which specifies the real address of the start of said page portion in said memory; and

    concatenating said page frame number with said displacement portion to obtain said real address.

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