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MESS wd177xx bug and NitrOS-9

  • Robert Gault
    Robert Gault

    A code change in MESS going from v136b to v137b had a major impact on the NitrOS-9 project. I have reported the bug to MESS and part of it has been fixed but don't know what to expect for the remaining part.
    A things now stand, the boot bug fix in the Boot module will fail in MESS 137b and possibly any later versions. Since many users of NitrOS-9 work on emulator systems, specifically MESS, we could have problems.

    The bug impacts here in the boot_1773.asm code.

             ldx   ,s get X saved earlier
    * Sector READ Loop
    L0123    lda   DATAREG,y read from WD DATA register
             sta   ,x+
    *         stb   >DPort+CONTROL *This is normal but causes the notorious boot bug. It was replaced by the next line.
             bra   L0123

    Unless MESS accommodates us with a correction, the original line with stb must be used with MESS emulation.

  • Robert Gault
    Robert Gault

    Sorry, there is a major bug interaction but it is not caused by the boot bug fix. Don't know just what is going on at the moment.

    If someone else wants to try and find out why Level2 will not boot in MESS 137, it would help us and the MESS team to report the reason.