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An eight-bit processor like the Intel 8008 addresses eight bits, but as this is the full width of the accumulator and other registers, this could be considered either byte-addressable or word-addressable. 32-bit x86 processors, which address memory in 8-bit units but have 32-bit general-purpose registers and can operate on 32-bit items with a ...
Memory-mapped files are becoming more difficult to implement in 32-bit architectures as files of over 4 GB become more common; such large files cannot be memory-mapped easily to 32-bit architectures, as only part of the file can be mapped into the address space at a time, and to access such a file by memory mapping, the parts mapped must be ...
For example, an 8-bit-byte-addressable machine with a 20-bit address bus (e.g. Intel 8086) can address 2 20 (1,048,576) memory locations, or one MiB of memory, while a 32-bit bus (e.g. Intel 80386) addresses 2 32 (4,294,967,296) locations, or a 4 GiB address space. In contrast, a 36-bit word-addressable machine with an 18-bit address bus ...
Another example in the same computer family was the 16-bit protected mode of the 80286 processor, which, though supporting only 16 MB of physical memory, could access up to 1 GB of virtual memory, but the combination of 16-bit address and segment registers made accessing more than 64 KB in one data structure cumbersome.
Because of this, the lowest 3 bits of a heap reference will always be 0. By lowering the resolution of 32-bit references to 8 byte blocks, the addressable space can be increased to 32 GB. This significantly reduces memory use compared to using 64-bit references as Java uses references much more than some languages like C++. Java 8 supports ...
These processors have 8-bit CPUs with 8-bit data and 16-bit addressing. The memory on these CPUs is addressable at the byte level. This leads to a memory addressable limit of 2 16 × 1 byte = 65,536 bytes or 64 kilobytes.
An n-byte aligned address would have a minimum of log 2 (n) least-significant zeros when expressed in binary. The alternate wording b-bit aligned designates a b/8 byte aligned address (ex. 64-bit aligned is 8 bytes aligned). A memory access is said to be aligned when the data being accessed is n bytes long and the datum address is n-byte
However, "client" versions of 32-bit Windows (Windows XP SP2 and later, Windows Vista, Windows 7) limit physical address space to the first 4 GB for driver compatibility [16] even though these versions do run in PAE mode if NX support is enabled. Windows 8 and later releases will only run on processors which support PAE, in addition to NX and SSE2.