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In the x86 assembly language, the TEST instruction performs a bitwise AND on two operands.The flags SF, ZF, PF are modified while the result of the AND is discarded. The OF and CF flags are set to 0, while AF flag is undefined.
Such address translations are carried out by the segmentation unit of the CPU. The last segment, FFFFh (65535), begins at linear address FFFF0h (1048560), 16 bytes before the end of the 20 bit address space, and thus, can access, with an offset of up to 65,536 bytes, up to 65,520 (65536−16) bytes past the end of the 20 bit 8088 address space.
Store to memory using Direct Store (memory store that is not cached or write-combined with other stores). 3 Tiger Lake, Tremont, Zen 5: MOVDIR64B Move 64 bytes as Direct Store. MOVDIR64B reg,m512: 66 0F 38 F8 /r: Move 64 bytes of data from m512 to address given by ES:reg. The 64-byte write is done atomically with Direct Store. [ai] 3 Tiger Lake ...
If that memory is arranged in a byte-addressable flat address space using 8-bit bytes, then there are 65,536 (2 16) valid addresses, from 0 to 65,535, each denoting an independent 8 bits of memory. If instead it is arranged in a word-addressable flat address space using 32-bit words, then there are 16,384 (2 14 ) valid addresses, from 0 to ...
The basic unit of digital storage is a bit, storing a single 0 or 1.Many common instruction set architectures can address more than 8 bits of data at a time. For example, 32-bit x86 processors have 32-bit general-purpose registers and can handle 32-bit (4-byte) data in single instructions.
For instance, a computer said to be "32-bit" also usually allows 32-bit memory addresses; a byte-addressable 32-bit computer can address 2 32 = 4,294,967,296 bytes of memory, or 4 gibibytes (GiB). This allows one memory address to be efficiently stored in one word. However, this does not always hold true.
A memory address a is said to be n-byte aligned when a is a multiple of n (where n is a power of 2). In this context, a byte is the smallest unit of memory access, i.e. each memory address specifies a different byte. An n-byte aligned address would have a minimum of log 2 (n) least-significant zeros when expressed in binary.
2 bytes (code) CP/M-80-like exit (always contains INT 20h) [1] [2] 02h–03h word (2 bytes) Segment of the first byte beyond the memory allocated to the program 04h byte Reserved 05h–09h 5 bytes (code) CP/M-80-like far call entry into DOS, and program segment size [1] [3] 0Ah–0Dh dword (4 bytes) Terminate address of previous program (old ...