The 16-bit processors: origin of x86

8086

• Introduced June 8, 1978
• Clock speeds:
• 5 MHz with 0.33 MIPS
• 8 MHz with 0.66 MIPS
• 10 MHz with 0.75 MIPS
• The memory is divided into odd and even banks. It accesses both the banks simultaneuosly in order to read 16 bit of data in one clock cycle.
• Bus Width 16 bits data, 20 bits address
• Number of Transistors 29,000 at 3 µm
• Addressable memory 1 megabyte
• Up to 10X the performance of 8080 (typically lower)
• Used in portable computing, and the IBM PS/2 Model 25 and Model 30
• Used segment registers to access more than 64 KB of data at once, bane of programmers' existence for years to come

8088

• Introduced June 1, 1979
• Clock speeds:
• 4.77 MHz with 0.33 MIPS
• 9 MHz with 0.75 MIPS
• Internal architecture 16 bits
• External bus Width 8 bits data, 20 bits address
• Number of Transistors 29,000 at 3 µm
• Addressable memory 1 megabyte
• Identical to 8086 except for its 8 bit external bus (hence an 8 instead of a 6 at the end)
• Used in IBM PCs and PC clones

MCS-86 Family

• 8086-CPU
• 8087-Math-CoProcessor
• 8088-CPU
• 8089-Input/Output Co-Processor
• 8208-Dynamic RAM Controller
• 8284-Clock Generator & Driver
• 8286-Octal Bus Transceiver
• 8287-Octal Bus Transceiver
• 8288-Bus Controller
• 8289-Bus Arbiter

80186

• Introduced 1982
• Used mostly in embedded applications - controllers, point-of-sale systems, terminals, and the like
• Used in several MS-DOS non-PC-Compatible computers including RM Nimbus, Tandy 2000
• Included two timers, a DMA controller, and an interrupt controller on the chip in addition to the processor
• Later renamed the iAPX 186

80188

• A version of the 80186 with an 8-bit external data bus
• Later renamed the iAPX 188

80286

• Introduced February 1, 1982
• Clock speeds:
• 6 MHz with 0.9 MIPS
• 8 MHz, 10 MHz with 1.5 MIPS
• 12.5 MHz with 2.66 MIPS
• 16 MHz, 20 MHz and 25 MHz available.
• Bus Width 16 bits
• Included memory protection hardware to support multitasking operating systems with per-process address space
• Number of Transistors 134,000 at 1.5 µm
• Addressable memory 16 MB (16 MB)
• Added protected-mode features to 8086 with essentially the same instruction set
• 3-6X the performance of the 8086
• Widely used in IBM-PC AT and AT clones at the time