it looks suspicious to me, like the kind of thing you find on page 30 of a processor errata document, something like "single writes to external device fail 0.5%

it looks suspicious to me, like the kind of thing you find on page 30 of a processor errata document, something like "single writes to external device fail 0.5% of the time due to a register clearing bug on mask revisions prior to version 23. recommended workaround: write twice."