Address control system for segmented buffer memory

• US 4,905,184 A
• Filed: 09/21/1987
• Issued: 02/27/1990
• Est. Priority Date: 09/21/1987
• Status: Expired due to Term

• Current Assignee: Unisys Corporation Detroit Michigan A Corporation of
• Original Assignee: Unisys Corporation
• Inventors: Reeve, Jeffrey T., Giridhar, Rangaswamy P.
• Primary Examiner(s): Zache, Raulfe B.
• Assistant Examiner(s): Pappas, George C.
• Application Number:
  US07/099,447
• Time in Patent Office: 890 Days
• Field of Search: 364/200 MS File, 364/900 MS File
• US Class Current: 710/52
• CPC Class Codes: G06F 13/122 where hardware performs an I/O function other than control of data transfer
• CPC Class Codes: G06F 3/0601 Interfaces specially adapted for storage systems
• CPC Class Codes: G06F 3/0656 Data buffering arrangements

Abstract

A buffer memory in a peripheral controller has dedicated page and word location segments for each one of a multiple number of attached peripheral units. Additionally, an auxiliary segment provides memory for the active status of each one of the multiple number of data transfer cycle operations which may be occurring concurrently and which status can be accessed at the optimum time so that each initiated data transfer cycle can be completed in a time-saving fashion. Memory address control means are provided for accessing page segments and word locations therein in order to insert data therein or to remove data therefrom. A special queue segment is available to provide concurrent status information for each I/O command initiated by a host computer.

Claims

1. A control system for permitting multiple simultaneous I/O data transfer cycles, in a peripheral controller, to be executed between a host computer which initiates I/O data transfer commands, and multiple numbers (n) of peripheral terminal units, the combination comprising:

(a) a segmented buffer memory means having "n+1" addressable page segments and "m" addressable word locations in each of the first "n" of said page segments and wherein

(i) each one of said addressable page segments, except the "n+1"th segment, is exclusively dedicated to a different one of said "n" peripheral terminal units;

(ii) said "n+1"th segment includes;

(iia) "n" scratch pad areas, addressable by a scratch pad address register, such that one of said "n" scratch pad areas is exclusively dedicated to a different one of said "n" peripheral terminal units and each one of said "n" scratch pad areas functions to hold status information on the status of each I/O instruction initiated by a processor means;

(b) memory address means for addressing page segments and word locations in said segmented buffer memory means, said memory address means including;

(b1) a peripheral address register, controlled by an arithmetic logic unit, for selecting one of said "n+1" page segments and "m" word locations for data being transferred out of said buffer memory means to a selected peripheral terminal unit or for data being transferred from a selected peripheral terminal unit to said buffer memory means;

(b2) a system address register, controlled by said arithmetic logic unit, for selecting one of said "n+1" page segments and "m" word locations for data being transferred from said host computer to said buffer memory means or for data being transferred from said buffer memory means to said host computer;

(b3) said scratch pad address register for addressing only the "n+1" page segment and the "m" word locations therein;

(c) said processor means including an arithmetic logic unit for controlling the execution of data transfers and for controlling said peripheral, system, and scratch pad address registers.

2. The system of claim 1 wherein each of said "n" page segments holds two blocks of data.

3. The system of claim 2 wherein each said block of data consists of 512 bytes.

4. The system of claim 1 wherein the said "n+1"th page segment provides memory locations to store each incompleted I/O data transfer command and information as to its present status of incompletion.

5. The system of claim 4 wherein said scratch pad address register selects locations in said "n+1"th page segment to record the said status of incompletion of each extant I/O command that was initiated, and wherein said selection of location is directed to the said scratch pad area dedicated to the particular peripheral terminal unit addressed by the particular I/O command involved with that particular terminal unit.

6. In a peripheral controller which manages data transfer cycles between a host computer, which initiates data transfer commands, and a plurality of "n" attached peripheral units,

a system for enabling the simultaneous and concurrent execution of a multiple number of I/O data transfer cycles, comprising in combination:

(a) buffer memory means having a plurality of "n" page-segments such that at least one page-segment is dedicated to each one of said plurality of "n" peripheral units, said buffer memory means including;

(a1) an auxiliary "n+1"th page-segment for storing each initiated data transfer command and its status of completion/incompletion, said "n+1"th page-segment including "n" scratch pad areas wherein each scratch pad area is dedicated for holding status information on I/O operations between said host computer and an associated one of said "n" peripheral units;

(a2 ) "m" data storage locations in each said page-segment;

(b) address means for accessing said page-segments and data storage locations for storage data undergoing transfer into or retrieving data undergoing transfer out of said data storage locations, said address means including;

(b1) means for accessing any selected one of said dedicated scratch pad areas in said "n+1"th page-segment;

(c) processor means for executing said initiated data transfer commands and including;

(c1) arithmetic logic unit means for controlling said address means to enable temporary storage, in said buffer memory means, of data undergoing transfer to/from each of said peripheral units and from/to said host computer.

7. The system of claim 6 wherein said address means includes:

(a) a system address register for addressing one of said dedicated buffer memory page-segments for insertion or retrieval of a block of data being transferred between said buffer memory means and a said host computer;

(b) a peripheral address register for addressing one of said dedicated buffer memory page-segments for insertion or retrieval of a block of data being transferred between said buffer memory means and a selected peripheral unit;

(c) a scratch pad address register for addressing locations in said auxiliary "n+1" page-segment for storage of status data as to the completion/incompletion status of each initiated data transfer command.

8. The system of claim 7 which includes:

(a) block counter means controlled by said peripheral address register, for counting each 512 byte block of data transferred between each said dedicated page segment of said buffer memory means and its associated peripheral unit.

9. The system of claim 6 wherein said processor means includes:

(a) means for scanning said auxiliary "n+1"th page-segment to find the status of each initiated data transfer command and to enable completion of each said initiated data transfer command at the next optimum time period available.

10. The system of claim 7 wherein each of said system-address, peripheral-address, and scratch-pad registers includes:

(a) a first register portion for storing a page-segment address for said buffer memory means;

(b) a second register portion for storing a specific word location address within the said page-segment addressed by said first register portion.

11. The system of claim 6 wherein each of said plurality of "n" page-segments includes at least sufficient locations for storing two blocks of data transfer words.

12. The system of claim 11 wherein each said block of words includes 512 bytes.

13. The system of claim 6 wherein said processor means includes:

(a) means to store, in any one of said scratch pad areas, the number status of words transferred on any initiated data transfer command cycle and to subsequently access said number status in order to complete the entire data transfer cycle, at the next optimumly available time period, to its full completion.