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In 8-bit CP/M versions it is located in the first 256 bytes of memory, hence its name. The equivalent structure in DOS is the Program Segment Prefix (PSP), a 256-byte (page-sized) structure, which is by default located exactly before offset 0 of the program's load segment, rather than in segment 0.
The zero page or base page is the block of memory at the very beginning of a computer's address space; that is, the page whose starting address is zero. The size of a page depends on the context, and the significance of zero page memory versus higher addressed memory is highly dependent on machine architecture.
In computer architecture, 256-bit integers, memory addresses, or other data units are those that are 256 bits (32 octets) wide. Also, 256-bit central processing unit (CPU) and arithmetic logic unit (ALU) architectures are those that are based on registers , address buses , or data buses of that size.
One of the major improvements the PCI Local Bus had over other I/O architectures was its configuration mechanism. In addition to the normal memory-mapped and I/O port spaces, each device function on the bus has a configuration space, which is 256 bytes long, addressable by knowing the eight-bit PCI bus, five-bit device, and three-bit function numbers for the device (commonly referred to as the ...
Similarly, a page frame is the smallest fixed-length contiguous block of physical memory into which memory pages are mapped by the operating system. [1] [2] [3] A transfer of pages between main memory and an auxiliary store, such as a hard disk drive, is referred to as paging or swapping. [4]
The address and value parameters may contain expressions, as long as the evaluated expressions correspond to valid memory addresses or values, respectively.A valid address in this context is an address within the computer's address space, while a valid value is (typically) an unsigned value between zero and the maximum unsigned number that the minimum addressable unit (memory cell) may hold.
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Most [citation needed] operating systems for the z/Architecture, including z/OS, generally restrict code execution to the first 2 GB (31 address bits, or 2 31 addressable bytes) of each virtual address space for reasons of efficiency and compatibility rather than because of architectural limits. Linux on IBM Z allows code to execute within 64 ...