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A status register, flag register, or condition code register (CCR) is a collection of status flag bits for a processor.Examples of such registers include FLAGS register in the x86 architecture, flags in the program status word (PSW) register in the IBM System/360 architecture through z/Architecture, and the application program status register (APSR) in the ARM Cortex-A architecture.
In computer architecture, predication is a feature that provides an alternative to conditional transfer of control, as implemented by conditional branch machine instructions. Predication works by having conditional ( predicated ) non-branch instructions associated with a predicate , a Boolean value used by the instruction to control whether the ...
Contained within the PSW are the two bit condition code, representing zero, positive, negative, overflow, and similar flags of other architectures' status registers. Conditional branch instructions test this encoded as a four bit value, with each bit representing a test of one of the four condition code values, 2 3 + 2 2 + 2 1 + 2 0. (Since IBM ...
The FLAGS register is the status register that contains the current state of an x86 CPU.The size and meanings of the flag bits are architecture dependent. It usually reflects the result of arithmetic operations as well as information about restrictions placed on the CPU operation at the current time.
In computer architecture, ... were changed to implement predictions based on the current values of the indicator bits (corresponding to today's condition codes). ...
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:
In computer science, an instruction set architecture (ISA) is an abstract model that generally defines how software controls the CPU in a computer or a family of computers. [1] A device or program that executes instructions described by that ISA, such as a central processing unit (CPU), is called an implementation of that ISA.
A race condition can arise in software when a computer program has multiple code paths that are executing at the same time. If the multiple code paths take a different amount of time than expected, they can finish in a different order than expected, which can cause software bugs due to unanticipated behavior.