I have faced such problem, apparently, it is mistake FASM. At attempt to compile a command

FASM 1.67.7 gives out error "Value out of range", thus such command exists, its opcode such - db 48h, 0F7h, 0C1h, 80h, 80h, 80h, 80h. At processing a command, for example,

FASM fulfils correctly.

The 32-bit immediate in 64-bit instructions is sign-extended, thus 48-F7-C1-80-80-80-80 is an opcode for "test rcx,0FFFFFFFF80808080h" (or "test rcx,-7F7F7F80h"), not for "test,rcx,80808080h".

Oh, I have understood, thanks.

if this isn't in FAQ, then it definitively should be....

In FAQ absolutely there is no branch on problems and features x64-86 assembler

it's x86-64

Yes, yes, x86-64, it's right. But as one my old friend spoke, it is not important as I have told, the main thing, that me have understood

vid: however which one FAQ did you mean?

I'm considering removing it, as the FAQs on this board tend to be better developing.

well, but seems nobody reads those...
having faq on board is imho too unstandard for most users.

also it's better to have all Qs and As in one file, not to need to load thread for every problem and read all crap there

So we can write a true FAQ here instead of just collection of links.

yup... and split that first-read-this into separate thread imho.

Perhaps it should be just rewritten from scratch. The "Important threads" has alteady taken the role of holding the links.

yup - without scary long header with lot of confusing letters