Am386
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The Am386 CPU was released by AMD in 1991. A 100%-compatible clone of the Intel 80386 design, it sold millions of units and positioned AMD as a legitimate competitor to Intel, rather than just a second source for Intel's x86 CPUs.
While the CPU was essentially ready to be released prior to 1991, Intel kept it tied up in court. AMD had previously been a second-source manufacturer of Intel's designs, and AMD's interpretation of the contract was that it covered all of them. Intel, however, claimed that the contract only covered the 80286 and prior processors. After a few years in the courtrooms, AMD finally won the case and the right to sell their Am386. This paved the way for competition in the CPU market and thus lowered the cost of owning a PC.
While Intel's 386 design peaked at 33 MHz, AMD released a 40 MHz version of both its 386DX and 386SX, extending the lifespan of the architecture. The AMD 386DX-40 was popular with small manufacturers of PC clones and with budget-minded computer enthusiasts because it offered near-80486 performance at a much lower price than a real 486.
Other than its high core clock speed, this performance was made possible because the Am386DX-40 ran its front side bus at the same 40 MHz speed as the processor itself, while the fastest 486 of the time ran with a 33 MHz FSB. Because the DX line of 386s used the same 32-bit data bus width as 486, the Am386DX-40 had superior memory and I/O performance compared to many 486s. Performance could be further boosted with the addition of an inexpensive 80387 math coprocessor, although the floating point performance was nowhere near that of the 486DX. Integer performance at 40 MHz approached that of low-end 486 CPUs but rarely, if ever, exceeded it because the 486 CPUs performed more instructions per clock cycle. 486 CPUs also enjoyed an immensely beneficial L1 cache. The Am386DX-40 chip sold well, first as a mid-range contender, and then as a budget CPU.
Although the processor struggled under Windows 95's increased CPU and memory requirements, it was sold into the mid-1990s. It was used both as an embedded chip and on budget motherboards for those who were only interested in running MS-DOS or Windows 3.1x applications.
[edit] External links
- AMD.com: Am386 Family 32-bit Processors
- cpu-collection.de: Pictures
- AMD: 30 Years of Pursuing the Leader. Part 2
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