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Their 32-bit linear addresses can address 4 billion different items. Using word addressing, a 32-bit processor could address 4 Gigawords; or 16 Gigabytes using the modern 8-bit byte. If the 386 and its successors had used word addressing, scientists, engineers, and gamers could all have run programs that were 4x larger on 32-bit machines.
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 32-bit register can store 2 32 different values. The range of integer values that can be stored in 32 bits depends on the integer representation used. With the two most common representations, the range is 0 through 4,294,967,295 (2 32 − 1) for representation as an binary number, and −2,147,483,648 (−2 31) through 2,147,483,647 (2 31 − 1) for representation as two's complement.
The addressing modes listed below are divided into code addressing and data addressing. ... full 32-bit address. ... as "zero page" addressing. The initial 256 bytes ...
The default OperandSize and AddressSize to use for each instruction is given by the D bit of the segment descriptor of the current code segment - D=0 makes both 16-bit, D=1 makes both 32-bit. Additionally, they can be overridden on a per-instruction basis with two new instruction prefixes that were introduced in the 80386:
With byte addressing, each code point can be placed in its own independently-addressable MAU with no overhead. With 32-bit word addressing, placing each code point in a separate MAU would increase the memory usage by 300%, which is not viable for programs that work with large amounts of text.
The byte count is always 04, the address field is 0000 and the first two data bytes are the CS value, the latter two are the IP value. The execution should start at this address. : 04 0000 03 00003800 C1: 04: Extended Linear Address Allows for 32 bit addressing (up to 4 GiB). The byte count is always 02 and the address field is ignored ...
IO5 is a 5-bit I/O address covering the bit-addressable part of the I/O address space, i.e. the lower half (range: 0–31) IO6 is a 6-bit I/O address covering the full I/O address space (range: 0–63) D16 is a 16-bit data address covering 64 KiB; in parts with more than 64 KiB data space, the contents of the RAMPD segment register is prepended