Hello, , you wrote: > Hello, netch80, you wrote: N>> Not "what for", and "why". I understand that the author too polite in relation to commands and Intel, and AMD. In a forum of such restriction is not present, and I can openly say that both firms frankly all possibilities which to them were given at first by passage 16> 32, then 32> 64, in respect of manufacture of equal and convenient command system. Presence of all of these SIL - frank ghost effect of curve design. > well, I would not become so to accuse in curvature. Most likely, statistics of usage of commands was really processed by development of new architecture. Forces and means for it were selected the big. At first, said that AMD created amd64 in a terrible time trouble (before it there was an idea to make a sandwich from x86 in 32 and Alpha in 64, but failed because of sale Alpha in parts). So could be without "forces and means". Secondly, curvature unconditionally is. Generally to save a format of commands x86 it is not necessary, it madly expensive to parallel analysis. N>> well I saw generation of its usage by compilers. In difference, for example, from ah/bh/ch/dh which do not lay down in the modern concepts of creation. > it is curious, in what cases compilers used SPL? I.e. what it were for commands? Transfers? I will specify - not spl, certainly. SP to change in a normal context it is impossible, and compilers simply do not generate in such, where SP (esp, rsp...) - the normal register. Meant sil, dil. I do not remember about bpl, quite could be in a mode omit-frame-pointer in the big function.