These are the stdio.asm changes that were present in the beta source code on Opus ][, but had been reverted in commit e3c0c962d4. As it turns out, the changes to stdio.asm were OK--the issue was simply that the definitions of stdin/stdout/stderr and the associated initialization code in vars.asm had not been updated to account for the new version of the FILE structure. That has now been done, allowing the changes to work properly.
This fixes#7.