diff --git a/BUGS/Magic 12 - Show.txt b/BUGS/Magic 12 - Show.txt index db0709ca8..1eea49cb3 100644 --- a/BUGS/Magic 12 - Show.txt +++ b/BUGS/Magic 12 - Show.txt @@ -16,3 +16,15 @@ Memory corruption bugs: first block in UMB, and DOSBox detects this as an "MCB list corrupted" error. + Workaround: + + You can avoid this crash/memory corruption by setting 'dos mem limit' + to a value less than 640 (such as 'dos mem limit=639') to mark off + the last 1KB of lower conventional memory as off-limits. If the demo + corrupts the bytes at segment 0x9FFF, it will have no effect and + DOSBox will no longer crash with "MCB list corrupted". It's possible + nobody ever caught the bug because most BIOSes by that point had + started taking the top 1KB under 640KB for the EBDA (extended BIOS + data area) and the corruption merely affected the unused trailing + end of it. +