Bug: Slow DOS App Performance Under Windows XP

Discussion in 'Parallels Desktop for Mac' started by drtimhill, May 9, 2006.

  1. drtimhill

    drtimhill Member

    Messages:
    85
    Others have flagged this elsewhere, but I thought I would write this up as a bug for the PW team...

    Problem
    Legacy MSDOS applications run *very* slowly under Windows XP in PW and cause Windows to pause for extended periods (several seconds).

    Scenario
    1. Start Windows XP in a Parallels VM (Professional was used for testing, Home probably exhibits the same behavior).

    2. Open a Command Prompt window by choosing Accessories -> Command Prompt from the Start menu.

    3. Execute a "DIR" command. Note that performance is fine, since at present Windows is running the 32-bit CMD.EXE app.

    4. Enter "COMMAND" and press Enter to load the legacy 16-bit MSDOS command prompt. Note that the new command prompt takes some time to appear (many seconds), since a legacy 16-bit app is now running.

    5. Enter "DIR" again. Note the *very* long delays before keystrokes are echoed. Also note that other Windows apps appear to hang, and that CPU utilization on the host (Mac) jumps up during this time.

    Other MSDOS apps also exhibit this behavior.

    --Tim
     
  2. andgarden

    andgarden Member

    Messages:
    34
    I strongly suspect that this accounts for much of the slowness in installing Windows 98.
     
  3. chrismasto

    chrismasto Member

    Messages:
    27
    This issue persists in the RC build. I just had to force kill a session, and I'm sure that's not something that should ever be necessary.
     

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