64-bit computing 64-bit computing In computer architecture, 64-bit computing is the use of processors that have datapath widths, integer size, and memory address widths of 64 bits (eight octets). Also, 64-bit computer architectures for central processing units (CPUs) and arithmetic logic units (ALUs) are those that are based on processor registers, address buses, or data buses of that size. From the software perspective, 64-bit computing means the use of code with 64-bit virtual memory addresses. However, not all 64-bit instruction sets support full 64-bit virtual memory addresses; x86-64 and ARMv8, for example, support only 48 bits of virtual address, with the remaining
Packed pixel Packed pixel In packed pixel or chunky framebuffer organization, the bits defining each pixel are grouped together. For example, if there are 16 bits per pixel, each pixel is represented in two consecutive (contiguous) 8-bit bytes in the framebuffer (a.k.a. screen buffer). If there are 4 bits per pixel (16 colors), each frame buffer byte defines two pixels, one in each nibble. The latter example is as opposed to storing perhaps half of the bits—2 bits—for each of four pixels in one byte and the other two bits for each of those four pixels in another byte or bytes. It