Does Core i7-900 processor have separate physical address/data pins for x87 FPU integrated coprocessor unit?
Posted on 2010-05-09 04:11:27 by logicman112
An integrated fpu has no external pins - it's built into the same physical package as the cpu.
Posted on 2010-05-09 04:45:35 by Homer
The FPU is not really an FPU since the first Pentium, IIRC. It's just additional instructions to the CPU. And in 64-bit mode, where you have guaranteed SSE, even those instructions are made dead (and I believe they'll be marked as obsolete in the very near future). It's kinda strange to ask for FPU's physical pins on a Core i7 ;P
Posted on 2010-05-09 09:58:35 by ti_mo_n
Thank you very much for the replies. The reason I guessed CPU has some pins for x87(or a protocol to access to a separate address space for FPU) was that the basic execution environment of IA-32 shows two registers:
48 bits FPU instruction pointer register
48 bits FPU data pointer register

It seems it has some pointers to access instruction/data , what are those then?
Posted on 2010-05-11 23:24:35 by logicman112
These are just for debugging, IIRC. I haven't really used FPU for a "while", so I don't remember correctly but there were registers which held last errorous instruction. I gues this is it. Everything is thoroughly explained in "Intel 64 and IA-32 Software Developer's Manual".
Posted on 2010-05-12 00:24:24 by ti_mo_n