Difference between revisions of "Intel 8086"

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[[Image:I8086.jpg|thumb|right|150px|i8086]]
 
[[Image:I8086.jpg|thumb|right|150px|i8086]]
The i8086 was the first generation x86 cpu.  The 8086 also had a cousin part, the 8088.  The 8088 had 8bit external IO bus, unlike the 8086 which was a full 16 bit cpu.
 
  
The 8086 had a 20 bit address bus, allowing for 1 megabyte of accessible memory.  However to maintain compatibility with the [[i8080|8080]] cpu that was popular in [[CP/M]] circles, the 8086 addressed memory in 64kb segments.  This would be seen as a major fault in the x86 architecture.
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The '''Intel 8086''' (also known as the '''i8086''') [[microprocessor]] was the first generation [[Intel x86|x86]] [[Central Processing Unit|CPU]]. The 8086 was a full 16-bit CPU, which means the internal [[data bus]], along with the external data bus.
  
The next cpu based on the 8086 was the [[i186|i80186]], although it didn't see widespread use, unlike the [[i286|i80286]] cpu.
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The 8086 had a 20 bit [[address bus]], allowing for 1 megabyte of accessible [[main memory]]. However, to maintain compatibility with the [[Intel 8080|8080]] CPU that was popular in [[CP/M]] circles, the 8086 addressed memory in 64KB [[segment]]s.  This would be seen as a major fault in the x86 [[architecture]].
  
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== 8088 ==
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The 8088 is the 'low cost' version of the 8086.  While it retained the same addressing modes, and instructions, the external data bus was 8 bits wide.  The 8088 was the primary CPU found in the [[IBM 5150|IBM PC]] and the [[IBM XT]].  This is why the original [[Industry Standard Architecture|ISA]] slots were 8 bit.
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The 8088 can be thought of sharing the same relationship with the 8086, as the [[Intel 80386SX]] had with the [[Intel 80386]].  While the data bus was restricted, the address bus was not, and the 8088 could still address a full megabyte of memory (in 64 KB segments).
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The next CPU based on the 8086 was the [[Intel 80186]], although it didn't see widespread use, unlike the [[Intel 80286]] CPU.
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[[Category: Intel Microprocessors]]

Latest revision as of 13:29, 3 November 2018

i8086

The Intel 8086 (also known as the i8086) microprocessor was the first generation x86 CPU. The 8086 was a full 16-bit CPU, which means the internal data bus, along with the external data bus.

The 8086 had a 20 bit address bus, allowing for 1 megabyte of accessible main memory. However, to maintain compatibility with the 8080 CPU that was popular in CP/M circles, the 8086 addressed memory in 64KB segments. This would be seen as a major fault in the x86 architecture.

8088

The 8088 is the 'low cost' version of the 8086. While it retained the same addressing modes, and instructions, the external data bus was 8 bits wide. The 8088 was the primary CPU found in the IBM PC and the IBM XT. This is why the original ISA slots were 8 bit.

The 8088 can be thought of sharing the same relationship with the 8086, as the Intel 80386SX had with the Intel 80386. While the data bus was restricted, the address bus was not, and the 8088 could still address a full megabyte of memory (in 64 KB segments).

The next CPU based on the 8086 was the Intel 80186, although it didn't see widespread use, unlike the Intel 80286 CPU.