8086: The First PC processor
The 8086 was the first x86 processor—Intel had already released the 4004, the 8008, the 8080 and the 8085. This 16-bit processor could manage 1 MB of memory using an external 20-bit address bus. The clock frequency chosen by IBM (4.77 MHz) was fairly low, though the processor was running at 10 MHz by the end of its career.
The first PCs used a derivative of this processor, the 8088, which had only an 8-bit (external) data bus. An interesting aside is that the control systems in the US space shuttles use 8086 processors and NASA was forced to buy some from eBay in 2002 since Intel could no longer supply them.
| Code name | N/A |
| Date released | 1979 |
| Architecture | 16 bits |
| Data bus | 16 bits |
| Address bus | 20 bits |
| Maximum memory | 1 MB |
| L1 cache | no |
| L2 cache | no |
| Clock frequency | 4.77-10 MHz |
| FSB | same as clock frequency |
| FPU | 8087 |
| SIMD | no |
| Fabrication process | 3,000 nm |
| Number of transistors | 29,000 |
| Power consumption | N/A |
| Voltage | 5 V |
| Die surface area | 16 mm² |
| Connector | 40-pin |
80286: 16 MB Of Memory, But Still 16 Bits
Released in 1982, the 80286 was 3.6 times faster than the 8086 at the same frequency. It could manage up to 16 MB of memory, but the 286 was still a 16-bit processor. It was the first x86 equipped with a memory management unit (MMU), allowing it to manage virtual memory. Like the 8086, it did not have a floating-point unit (FPU), but could use a x87 co-processor chip (80287). Intel offered these processors at a maximum frequency of 12.5 MHz, whereas their competitors reached 25 MHz.
| Code name | N/A |
| Date released | 1982 |
| Architecture | 16 bits |
| Data bus | 16 bits |
| Address bus | 24 bits |
| Maximum memory | 16 MB |
| L1 cache | No |
| L2 cache | No |
| Clock frequency | 6–12 MHz |
| FSB | same as clock frequency |
| FPU | 80287 |
| SIMD | No |
| Fabrication process | 1,500 nm |
| Number of transistors | 134,000 |
| Power consumption | N/A |
| Voltage | 5 V |
| Die surface area | 49 mm² |
| Connector | 68-pin |
386: 32-Bit and Cache Memory
Intel’s 80836 was the first x86 with a 32-bit architecture. Several versions of this processor were offered. The two best known are the 386 SX (Single-word eXternal), which had a 16-bit data bus, and the 386 DX (Double-word eXternal) with a 32-bit data bus. Two other versions are worth noting, though: the SL, which was the first x86 to offer management of a cache (external) and the 386EX, used in the space program (the Hubble telescope uses this processor).
| Code name | P3 |
| Date released | 1985 |
| Architecture | 32 bits |
| Data bus | 32 bits |
| Address bus | 32 bits |
| Maximum memory | 4096 MB |
| L1 cache | 0 KB (controller sometimes present) |
| L2 cache | no |
| Clock frequency | 16-33 MHz |
| FSB | same as clock frequency |
| FPU | 80387 |
| SIMD | no |
| Fabrication process | 1,500-1,000 nm |
| Number of transistors | 275,000 |
| Power consumption | 2 W @ 33 MHz |
| Voltage | 5 V |
| Die surface area | 42 mm² @ 1µ |
| Connector | 132 pins |
The 486: An FPU And Multipliers Too
The 486 is emblematic of a certain generation who were first discovering computers. In fact, the very famous 486 DX2/66 was long considered the minimum configuration for gamers. This processor, released in 1989, ushered in several interesting new features, like an on-chip FPU, data cache, and the first clock multiplier. The former consisted of an x87 coprocessor built into the 486 DX (not SX) series. An 8 KB Level 1 cache was built into the processor (write-through type, then write-back with slightly better performance). There was also the possibility of a Level 2 cache on the motherboard (at the bus frequency).
The second generation of 486s had a CPU multiplier, since the processor operated faster than the FSB, with DX2 (2x multiplier) and DX4 (3x multiplier) versions. Another anecdote: the “487SX” sold as an FPU for the 486SX was actually a full 486DX that disabled and took the place of the first processor.
| Code name | P4, P24, P24C |
| Date released | 1989 |
| Architecture | 32 bits |
| Data bus | 32 bits |
| Address bus | 32 bits |
| Maximum memory | 4096 MB |
| L1 cache | 8 KB |
| L2 cache | Motherboard (FSB frequency) |
| Clock frequency | 16-100 MHz |
| FSB | 16-50 MHz |
| FPU | On chip |
| SIMD | No |
| Fabrication process | 1,000–800 nm |
| Number of transistors | 1,185,000 |
| Power consumption | N/A |
| Voltage | 5 V–3.3 V |
| Die surface area | 81 - 67 mm² |
| Connector | 168 pins |
