Depends on how you define "common" but the entire lineage 8080 -> 8086 -> 8088 are backwards compatible and therefore are very much related.

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jacquesm 3 days ago | parent | next [-]

It goes further back than that, just not as backwards compatible. 4004 -> 8008, 8080 and so on. Just like the 6800, 6809, 68000 etc progression. All of these are families that have more in common with each other from one generation to the next than with other such families. It's logical: usually those were the same teams designing them with better tools and more money at their disposal, as well as a vastly increased transistor budget. Notable exception: the 6800 is in many ways simply an improved 6502 but by a different manufacturer.

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leoc 3 days ago | parent | next [-]

The 8008 is not a 4004 descendant, though: it was a new design originally done for the Datapoint 2200!

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jacquesm 3 days ago | parent | next [-]

Fair point, that's true in the direct lineage sense, but, 6809 to 68000 is a similar jump, there is nothing to say the one was based on the other except for general ideas and some addressing modes that turned out to be handy (when writing compilers, rather than writing assembly). Every widening of the databus caused a redesign from the ground up, even if some of the concepts survived. The 4004 was early enough that there was not much installed base to worry about so a clean start for a new chip made very good sense.

But in the 65XX family there is the 65816, a chip that tried really hard to maintain as much backward compatibility as possible. It saw some commercial deployment (Apple, Nintendo). At that point in time backwards compatibility began to have real value and intel really made some lucky calls: the weird addressing modes resulting from the lack of register width eventually culminated in a setup that worked very well for CPUs that were running multi-tasking OS's. The 386 was a very nice match for such code and this model was a major factor in the success of the line (which really was creaking badly with the 80286 out vs the 68K, which effectively had a 32 bit flat model built in because of its ability to run position independent code).

But in 1987, when the 80386 hit GA it was pretty much game over for the rest even if it took a while for the other empires to crumble, only ARM survived and that is mostly because Acorn had a completely different idea about power consumption and use of silicon than Intel did. The current crop of x86 hardware is insane in terms of power consumption and transistor count, ARM is so much more elegant (in spite of its warts).

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leoc 3 days ago | parent [-]

And a nearly opposite business model too: IIUC ARM was more or less the first company to behave like it actually wanted customers for its CPU-design licenses.

	▲	jacquesm 3 days ago \| parent [-]
		Yes, that's a very good observation, ARM was always an IP company rather than a one-stop-shop and that in turn served as a very effective avenue for the evangelism of its architecture.

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klelatti 3 days ago | parent | prev [-]

With Datapoint’s own ISA of course!

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tonyedgecombe 3 days ago | parent | prev [-]

Another similar exception is the Z80 to the 8080.

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jacquesm 3 days ago | parent [-]

That's Zilog, not Intel!

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tonyedgecombe 3 days ago | parent [-]

That's the point:

>Notable exception: the 6800 is in many ways simply an improved 6502 but by a different manufacturer.

	▲	jacquesm 3 days ago \| parent [-]
		Ah I see now what you meant.

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klelatti 4 days ago | parent | prev [-]

8080 -> 8086 not compatible although assembly code translation was possible.

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mananaysiempre 3 days ago | parent [-]

Some parts of the lineage are nevertheless very important. When I wrote a 8086 assembler, I’ve come across the idea of of writing the instruction encodings in octal instead of hexadecimal purely by accident, described as some sort of little-known neat trick hidden from the casual reader of the CPU documentation. It’s only by reading the manual for the Datapoint 2200 much later that I found a confirmation that this was very much intentional and (in the distant past) documented.

	▲	klelatti 3 days ago \| parent [-]
		100%! There is clear lineage back to the Datapoint 2200 which is remarkable given that it wasn't even an Intel design and CTC gave away the rights IIRC.