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Speed of Read vs Get — Parallax Forums

Speed of Read vs Get

ArchiverArchiver Posts: 46,084
edited 2004-07-15 20:22 in General Discussion
I was wondering if anyone had an idea of the difference in access
speed between READing from the EEPROM and GETtting from the
scratchpad. Is there a signficant difference or a slight difference?

Eric

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2004-07-15 15:50
    GET is accessing internal RAM while READ is accessing external (of the
    interpreter chip) EEPROM -- I've not measured but am confident that GET
    will be faster.

    -- Jon Williams
    -- Applications Engineer, Parallax
    -- Dallas Office

    Original Message
    From: Eric Berg [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=tDuquRrQ1LWcDnOL5mZSgAZxjNUsy7Dk8kC4JFcLM7oD0aQ1bzGneEAObJwU2Xj-Go6nIo51XWc]khufumen@y...[/url
    Sent: Thursday, July 15, 2004 9:35 AM
    To: basicstamps@yahoogroups.com
    Subject: [noparse][[/noparse]basicstamps] Speed of Read vs Get


    I was wondering if anyone had an idea of the difference in access
    speed between READing from the EEPROM and GETtting from the
    scratchpad. Is there a signficant difference or a slight difference?

    Eric
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-15 17:09
    GET is faster than READ. Something like a factor of 2/3. PUT is
    about the same as GET, but of course WRITE is verrrrry slow.

    -- Tracy


    >I was wondering if anyone had an idea of the difference in access
    >speed between READing from the EEPROM and GETtting from the
    >scratchpad. Is there a signficant difference or a slight difference?
    >
    >Eric
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-15 19:37
    I found my note, and GET has a bigger speed advantage over READ than
    I remembered

    on a BS2pe:
    GET 140 to 155 microseconds
    PUT 140 to 155 microseconds

    READ 620 to 645 microseconds
    WRITE 3500 to ??? microseconds

    That is more than 4x advantage, which could add up if it is part of a
    time-critical loop.

    The times were measured on a BS2pe, so if you have a= BS2p, divide
    those times by 2.5, except for WRITE, which would be about the same.

    -- Tracy





    >GET is faster than READ. Something like a factor of 2/3. PUT is
    >about the same as GET, but of course WRITE is verrrrry slow.
    >
    > -- Tracy
    >
    >
    >>I was wondering if anyone had an idea of the difference in access
    >>speed between READing from the EEPROM and GETtting from the
    >>scratchpad. Is there a signficant difference or a slight difference?
    >>
    > >Eric
  • ArchiverArchiver Posts: 46,084
    edited 2004-07-15 20:22
    Thanks Tracy,
    I'm running out of room on the scratchpad. 2/3 isn't
    bad at all. Thanks again.
    Eric
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