386(redirected from 80387)
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386The first 32-bit CPU in, and third generation of, the Intel x86 family. The term may refer to the chip or to a PC that used it. Introduced in late 1985, it was the successor to the 286, and although adequate for DOS, it was slow for Windows and other graphics-based programs. It was the first x86 chip to unify memory management and allocate both extended and expanded (EMS) memory on demand. It also added Virtual 8086 Mode, which allowed multiple DOS applications to be multitasked side-by-side with Protected Mode (32-bit) applications. The 386 architecture was followed in all subsequent x86 chips. See PC and x86.
Type: 32-bit multitasking microprocessor
Transistors: 275,000 (1.5 micron)
Package: 132-pin PGA
Registers: 32 32-bit
Real Mode: Performs as a 16-bit 8086 CPU; addresses 1MB memory.
Protected Mode: Addresses 4GB physical and 64TB virtual memory; provides access to memory protection and 32-bit instructions.
Virtual 8086 Mode: Protected Mode subset that runs a Real Mode application in a virtual machine.