The x86 architecture has a long and convoluted history dating back to 1978, when Intel announced the 16-bit 8086 microprocessor. IBM selected the 8086 and its cousin, the 8088, for IBM’s first personal computers. In 1985, Intel introduced the 32-bit 80386 microprocessor, which was backward ...
The 8086 microprocessor provided eight 16-bit registers. It could separately access the upper and lower eight bits of some of these registers. When the 32-bit 80386 was introduced, the registers were extended to 32 bits. These registers are called EAX, ECX, EDX, EBX, ESP, EBP, ESI, and...
A method for executing instructions of a computer program in a processor is also described. The method comprises executing a first instruction of a first instruction set, executing a first switch instruction, switching from a first instruction set mode to a second instruction set mode, and executin...
The 8086 Instruction Format vary from 1 to 6 bytes in length. Fig. 6.8 shows the instruction formats for 1 to 6 bytes instructions.
Although now mostly forgotten, the Datapoint 2200 was the origin of the 8-bit microprocessor, as I'll explain below. The Datapoint 2200 computer (Version II). The memory storage of the Datapoint 2200 had a large impact on its architecture and thus the architecture of today's computers. ...
instructionsetarchitecture
The String Instruction in 8086 are namely, REP is a prefix which is written before one of the string instructions. These instructions repeat
A simplified method and apparatus for handling the change of instruction control flow in a microprocessor is provided. Rather than attempting to implement a change in the instruction flow immediately, the processor first recognizes that flow is to be redirected from a predicted instruction flow to a...
The number of such micro-instructions (or "machine cycles") required to execute an average CPU instruction depends on the power (hence cost) of the underlying microprocessor, the complexity of the CPU architecture, and the application being run (i.e., the instruction mix). Typically, for ...
Figure 3 is a table of the Coprocessor instructions available in the system of Figure 1. Figures 4a and 4b illustrate the Coprocessor state format and Format word, respectively, in the system of Figure 1. Figure 5 is the address structure which enables the Processor to uniquely access the Cop...