64-bit is an attribute which is used in many ways in the field of computer technology. It is there, the demarcation of similar techniques with other bit number, usually half or twice the number of bits (in this case 32- bit and 128- bit). Without further context, it refers mostly to the alignment to a 64 -bit architecture ( " 64- bit Operating System", " 64 -bit PC "). 64 bits are mathematically a 64 digits long series of ones and zeros.
In connection with the processors is often the question of different generations, the difference lies substantially in the width of the data paths of the respective ALU, there being with each doubling 8, 16, 32 and 64-bit ALUs. Analog is referred to as 64- bit CPUs.
In computer technology one finds the 64- bit attribute frequently for:
- 64- bit main processor ( engl. Central Processing Unit, CPU) - the name of the ALU computation width, mostly internal ( non- segmented ) address width
- 64- bit registers - usually when naming the coprocessors whose tabs are wider than the ALU register of the main processor
- 64 -bit memory ( engl. random access memory, RAM) - usually as cache the internal organization of the rare data paths to RAM module
- 64- bit cache line - organization of the cache in access lines, specifies the minimum size for transfer to the RAM.
- 64- bit video card - here means the data paths for its own graphics memory, followed by 128- bit and 256 -bit width
Where that does not have any system with 64 -bit signal data paths via 64 bit address paths. This can, in extreme cases continue to be in 32 bit mode ( 4 GiB address space ).