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Definition: 486


The fourth generation of the Intel x86 family of CPU chips. The term may refer to the chip or to a PC that used it. Introduced in 1989, it was the successor to the 386 and the first chip in the line to include a built-in math coprocessor. Providing acceptable performance for DOS, it was bare minimum for Windows. Later versions of the chip doubled and tripled internal speeds (see DX2 and DX4). See OverDrive CPU, PC and x86.

Technical Specs
The 486 was a 32-bit CPU with thirty-two 32-bit registers and 1.1M to 1.2M transistors in a 168- or 169-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. Virtual 8086 Mode ran a Real Mode application in a virtual machine.