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.
The 386 was a 32-bit CPU with thirty-two 32-bit registers and 275,000 transistors in a 132-pin PGA package. Real Mode performed as an 8086 CPU that addressed 1MB of RAM, while Protected Mode addressed 4GB of physical RAM and 64TB of virtual memory.
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