8086 registers that are not visible to the programmer.) In the 8086, a memory cycle takes at least four clock cycles (called T1 through T4), including adding the segment register to compute the memory address. An "unaligned" memory access takes twice as long, though, because the 8086 has...
A String Instruction in 8086 is a series of the same type of data items in sequential memory locations. The CMPS instruction can be used to compare a byte in one string with a byte in another string or to compare a word in one string with a word in another string. SI is used to ho...
The 8086, like most processors, has an instruction register that holds the instruction that is currently being executed. In the 8086, the instruction register holds the first byte of an instruction (which may consist of multiple bytes), so it is built from eight latches (below). You might ...
The changes in the 286 include protected-mode operation, new instructions, and faster cycle times. The 386 chip has several significant changes. One of these changes is that the 386 is a 32-bit computer with support for paged virtual memory. 展开 ...
These are also useful in virtualization code. It makes it possible to update the virtual cycle counter without saving eflags, for example. 2) bitswap dst, src: Reverses all the bits in src and stores the result in dst. It's similar to bswap. This isn't incredibly common, but it comes...
The changes in the 286 include protected-mode operation, new instructions, and faster cycle times. The 386 chip has several significant changes. One of these changes is that the 386 is a 32-bit computer with support for paged virtual memory.MICHAEL L. SCHMIT...
then later changed during thedevelopment cycle. Remember, the bounds size must be the size of thedestination bufferand not that of the source. I have seen examples of dynamic checks that did astrlen()of the source string for number of bytes that were copied. This simple mistake invalidates ...
Superscalar microprocessors enable the execution of multiple instructions per clock cycle. These microprocessors accomplish this function by means of a built-in scheduler that identifies a group of instructions that will not conflict with each other or require simultaneous use of a particular service, ...
The x86 lineage began in 1978 with the 16-bit 8086 microprocessor. They are known as CISC - Complex Instruction Set Computing - processors. Unlike RISC, CISC instructions can perform complex tasks that take more than one cycle to execute. These can include floating-point mathematical calculations...
As shown in Figure 2a, the Processor initiates a write cycle to a Coprocessor by issuing the CPU Address Space Function Code and providing the address of the appropriate Coprocessor on the address bus. The Processor then asserts Address Strobe (AS) and negates Read/Write (R/W) to indicate ...