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Auto data transfer continue & retrun status

IP.com Disclosure Number: IPCOM000014619D
Original Publication Date: 1999-Dec-01
Included in the Prior Art Database: 2003-Jun-20
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Hiroshi Uchiike: AUTHOR [+3]

Abstract

Auto data transfer continue retrun status Disclosed is a method of reduction of microcode's overhead for command loading in SCSI-HDD assisted by Hardware. The traditional ways of command load is as below. 1. First , microcode prepare the parameter to check buffer memory is available or not.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 90% of the total text.

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Auto data transfer continue & retrun status

    Disclosed is a method of reduction of microcode's overhead for command loading
in SCSI-HDD assisted by Hardware.

The traditional ways of command load is as below.

1. First , microcode prepare the parameter to check buffer memory is available
or not.

(This check will execute by hardware)
2. Hardware issue interrupt when buffer is ready.
3. When microcode receive the interrupt , check next command can be load or
not. If OK , load command.
4. After write down the data to media actually , hardware issue interrupt.
5. When microcode receive the interrupt , return status to host.

In this method , overhead of microcode is large.

buffer is ready -> issue interrupt

                              A
Hardware works ·---------------|

····· |---------------------------|
A V
··········· execute next command After write data to media
actually , issue interrupt

          ·········decide next command can be executed or not
A
Microcode works ······|------| |--|
············ ······V· V
receive interrupt , start check receive
interrupt , return status

Our new method is

1. While hardware executing current command , microcode check next command can
be load or not.
2. When buffer is ready , hardware see the result of microcode's check(next
command can be load or not)
3. Hardware load command automatically , and execute.
4. When finish command , return status to host.

buffer is ready

                              A When finish command ,
return status to host
Hardware works ·-----------...