Intel 80486 - 1989         Intel i486 (also known as 80486 or 486) is the first Intel microprocessor with built-in FPU, which is actually what a co-processor really is (DX version only). i486 adopted the technology from RISC to improve the instruction executing speed at each cycle; it also has an enhanced bus interface to increase the data exchange speed between the CPU and memory. Because of those improvements, i486 DX is about 2 times faster than 386/387 at the same clock speed. However, the early i486 SX (486 without built-in FPU) is actually slower than some high-end 80386s. Starting from Intel i486, processor uses multipliers so the CPU can run at higher frequency than the mother board. Interestingly, SX version, which was released after DX version, sometimes is just a i486 DX with defected FPU; Intel closed its FPU and packaged it as SX version. At the time, many users who do not perform a lot arithmetic calculation (or just want to save money) often chose to buy the cheaper i486 SX, but if they found out that the performance is below their expectation, they would have to buy a 80487 SX FPU (co-processor); they would ended up spending more money than just buying a 80486 DX at beginning. In fact, Intel i486 DX was released earlier than SX, so the situation mentioned before was not happening very often. Therefore, 80487 SX became one of the uncommon chips in my collection. Intel i486 is also one of the favorite targets of cloning by other companies. The 80486SX 16Mhz at the right is the slowest product in the whole Intel i486 product line, so not many of them remains. The one below is 80486DX ES, which is the engineering sample of Intel i486 DX; another rarer item here. Process: 1,185,000 transistors (1 micron) and 900,000 transistors (0.8 micron) Package: 1168-pin Pin Grid Array Data Bandwidth: 32 bit Working Voltage: 5V Released Clock Speed(s) 16MHz - 100MHz Intel 80486 SX 16Mhz (A80486SX-16) [F] [B] Intel 80486 SX 20Mhz (A80486SX-20) [F] [B] Intel 80486 SX 25Mhz (A80486SX-25) [F] [B] Intel 80486 SX 25Mhz QFP (SB80486SX-25) [F] Intel 80486 SX 33Mhz (A80486SX-33) [F] [B] Intel 80486 SX2 50Mhz (A80486SX2-50) [F] [B] Intel 80486 SX 33Mhz PGA (FA80486SX-33) [F] [B] Intel 80486 SX 33Mhz QFP (KU80486SX-33) [F] [B] Intel 80486 SL 25Mhz QFP (KU80486SL-25) [F] Intel 80486 DX Engineering Sample (A80486DX ES) [F] [B] Intel 80486 DX 25Mhz (A80486DX-25) [F] [B] Intel 80486 DX 33Mhz (A80486DX-33) [F] [B] Intel 80486 DX 33Mhz by IBM (486DX-33) [F] [B] Intel 80486 DX 50Mhz (A80486DX-50) [F] [B] Intel 80486 DX2 50Mhz (A80486DX2-50) [F] [B] Intel 80486 DX2 40Mhz QFP (SB80486DX2-40) [F] Intel 80486 DX2 50Mhz QFP (SB80486DX2-50) [F] Intel 80486 DX2 66Mhz (A80486DX2-66) [F] [B] Intel 80486 DX2 66Mhz IBM OEM (486DX2-66) [F] Intel 80486 DX4 75Mhz (A80486DX2-75) [F] [B] Intel 80486 DX4 75Mhz QFP (FC80486DX4-75) [F] Intel 80486 DX4 100Mhz QFP (FC80486DX4-100) [F] Intel 80486 DX4 100Mhz (A80486DX4-100) [F] [B] Intel 80487 SX (A80487SX) [F] [B] 80486（簡稱486或是i486）是英特爾第一個內部包含浮點運算器（FPU）的中央處理器晶片（DX版CPU），並在x86系列中首次使用了RISC(精簡指令集)技術，從而提升了每週期執行指令的速度。486還採用了更進步的資料匯流排，大大提高了處理器與記憶體的資料交換速度。由於這些改進，同樣速度的i486DX的性能比擁有80387數學輔助運算器的80386快了兩倍有餘。不過486SX早期的產品反而比80386高階的產品還慢。 從80486 DX開始，浮點運算器開始內建於微處理器中，並開始使用倍頻，所以微處理器可以以比主機板更高的頻率運作。好笑的是，SX往往就是浮點運算器有問題的DX，英特爾把其浮點運算器關閉後拿來當SX賣。當時486也是一堆公司爭相仿冒的對象。當時對於數學運算比較不注重（或是想省錢）的用戶，都會選擇比較便宜的SX，可是當發現其運算能力不足的時候則需要添購80487浮點運算器，這樣花費反而不划算。可是其實較早推出的80486 DX早就內建了浮點運算器，所以這種情況很少會發生，當然80487也變成非常少見的產品。 右邊的 486SX 16Mhz 就是80486里面最慢的產品，數量很少，而其下面80486DX ES則是486的工程版，為486正式推出之前的樣本，也是鮮少見到的產品。 製程： 1,185,000 transistors (1 micron) and 900,000 transistors (0.8 micron) 封裝： 168-pin Pin Grid Array 資料頻寬： 32 bit 工作電壓： 5V 工作時脈： 16MHz - 100MHz Intel 80486 SX 16Mhz (A80486SX-16) 正 反 Intel 80486 SX 20Mhz (A80486SX-20) 正 反 Intel 80486 SX 25Mhz (A80486SX-25) 正 反 Intel 80486 SX 25Mhz QFP (SB80486SX-25) 正 Intel 80486 SX 33Mhz (A80486SX-33) 正 反 Intel 80486 SX2 50Mhz (A80486SX2-50) 正 反 Intel 80486 SX 33Mhz PGA (FA80486SX-33) 正 反 Intel 80486 SX 33Mhz QFP (KU80486SX-33) 正 反 Intel 80486 SL 25Mhz QFP (KU80486SL-25) 正 Intel 80486 DX Engineering Sample (A80486DX ES) 正 反 Intel 80486 DX 25Mhz (A80486DX-25) 正 反 Intel 80486 DX 33Mhz (A80486DX-33) 正 反 Intel 80486 DX 33Mhz by IBM (486DX-33) 正 反 Intel 80486 DX 50Mhz (A80486DX-50) 正 反 Intel 80486 DX2 50Mhz (A80486DX2-50) 正 反 Intel 80486 DX2 40Mhz QFP (SB80486DX2-40) 正 Intel 80486 DX2 50Mhz QFP (SB80486DX2-50) 正 Intel 80486 DX2 66Mhz (A80486DX2-66) 正 反 Intel 80486 DX2 66Mhz IBM OEM (486DX2-66) 正 Intel 80486 DX4 75Mhz (A80486DX2-75) 正 反 Intel 80486 DX4 75Mhz QFP (FC80486DX4-75) 正 Intel 80486 DX4 100Mhz QFP (FC80486DX4-100) 正 Intel 80486 DX4 100Mhz (A80486DX4-100) 正 反 Intel 80487 SX (A80487SX) 正 反
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