Intel's 15 Most Unforgettable x86 CPUs : 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.
Intel 8086
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