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Conference 49.910::kav30

Title:VAX on VMEbus: KAV30
Notice:Could have been as fast as 68K but its a VAX!
Moderator:CSSVMS::KAV30_SUPP
Created:Thu Apr 18 1991
Last Modified:Fri Aug 02 1996
Last Successful Update:Fri Jun 06 1997
Number of topics:159
Total number of notes:645

146.0. "EZDRIVER DMA timing too long. How to decrease it ?" by SWTHOM::VOUTERS () Thu Dec 08 1994 12:07

    Hello,
    
    This is about a VME300 board but it can be related to a KAV30. A
    customer observed that DMA done by EZDRIVER could last 18 microsec
    causing other boards accessing the DPRAM a bus error. He said
    that the specs should give 6 microsec. for DMA bursts at most.
    
    My question is how to decrease this DMA bus timing by the EZDRIVER
    for other boards not experiencing fatal bus errors ?
    
    Thank you in advance.
    Best regards,
    Philippe
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146.1bad luck...EICMFG::KAV30_SUPPThu Dec 08 1994 13:309
    Hi Phillipe,
    
    that is - unfortunately - a known problem, and if you use ELN and
    DECnet there is nothing you can do. 6 microseconds is the chip spec,
    18 microseconds is what the EZdriver does.... You could ask the
    ELN guys if they have a solution/fix/workaround... we have not heard of
    anything in this direction....
    
    Thomas
146.2see VAXELN conferenceSWTHOM::VOUTERSMon Dec 12 1994 14:422
    Posted in VAXELN Notesfile.
    Philippe