SEGMENT ADDRESSING

• US 3,725,874 A
• Filed: 09/02/1971
• Issued: 04/03/1973
• Est. Priority Date: 05/11/1968
• Status: Expired due to Term

• Current Assignee: Jean J. Marie D. Van Heel
• Original Assignee: Jean J. Marie D. Van Heel
• Inventors: Van Heel, Jean J. Marie D.
• Primary Examiner(s): Springborn, Harvey E.
• Application Number:
  US05/177,442
• Time in Patent Office: 579 Days
• Field of Search: 340/172.5
• US Class Current: 711/220
• CPC Class Codes: G06F 12/0292 using tables or multilevel address translation means G06F12/023 takes precedence; address translation in virtual memory systems G06F12/10
• CPC Class Codes: G06F 12/1036 for multiple virtual address spaces, e.g. segmentation G06F12/1045 takes precedence
• CPC Class Codes: G06F 12/145 the protection being virtual, e.g. for virtual blocks or segments before a translation mechanism
• CPC Class Codes: G06F 9/342 Extension of operand address space

Abstract

A computer comprising a store addressable in segments, containing segment words selectable by segment numbers, which words contain data of the segment, for example, a segment base address and a segment length information, in which two or three segment word registers are provided for storing two or particularly three segment words in order to ensure a rapid run of the programmes in the event of frequent change of addressing in a plurality of segments. The computer for this purpose with a detection device for detecting whether and, if so, in which of the in total two or three segment word registers the segment word of an indicated segment in a segment number register is stored. In the presence of the relevant segment word it is released via gates for calculating the address and for length check. In the absence of said segment word this word is carried on from the store to a segment word register. Particularly one of the three segment word registers is constantly reserved for storing the segment word of one given segment (O-segment).

Claims

1. A computer comprising a store addressable in a plurality of numbered word segments, each word segment having at least a segment base address portion and a segment length data portion, said store including a plurality of storage locations selectable by a segment number register wherein said segment words are stored, said computer further comprising converting means for converting logical segment addresses into numbered word segments for selecting said memory storage location, said converting means comprising a first segment word register having a first part thereof storing a segment base address portion and a second part storing a segment length data portion of one said numbered word segment, a register for storing a logical segment address to be converted, a summation device to address parts of the segment word register and the logical address register for combining said address parts to form a said numbered word segment, a comparison device for comparing said segment length data with said numbered word segment derived from the two said registers for checking whether said numbered word segment is located within said one numbered word segment, at least one further segment word register for storing the segment base address and the segment length data of at least one further segment contingent to said one numbered word segment, said segment number register responsive to said derived numbered word segment to select a said numbered word segment, a detection device responsive to the select segment number register contents for detecting if, and consequently in which of said two segment word registers the segment word of the derived numbered word segment is stored, said detection device including means for applying a control-signal to the relevant one of said two segment word registers, said detection device further having means responsive to the absence of the segment word of said derived numbered word segmenT in one of the two segment word registers for applying a control-signal to said numbered word register for transferring the segment word of said derived numbered word from the numbered word register to one of the segment word registers.

2. A computer as claimed in claim 1, wherein three segment word registers are provided and in that one of the segment word registers is constantly provided with a segment base address and a segment length information of a given segment.

3. A computer as claimed in claim 1, wherein storage locations selectable by segment numbers are provided with means for storing segment accessibility data, said segment word registers being provided with locations for storing said segment accessibility data.

4. A computer as claimed in claim 1, further providing for the segment addressing of a segment mode including segmented programmes as well as segment addressing in which programmes as a whole may be considered to form individual segments and wherein said computer comprises a control-device for producing a signal at the change over from one type of segment addressing to the other on a conductor, said signal capable of controlling said one of said segment word registers for storing the initial segment word of the relevant segment addressing mode.