Reading across difference lineage of CPU created by intel , many questions aroused in my head that need to be solved . The questions are as follow :
In terms of what difference that makes both the architecture of 8085 and 8086 differ that makes intel name both of this architecture differently ?
Note : My friend told me 8085 is an 8-bit microprocessor but 8086 is a 16-bit processor , this is what makes them different from each other and that’s why , one is called 8085 and the other is called 8086 . But as far as I know most of the CPU we’re using right now are currently called 80×86 architecture based on the 8086 cpu and it has 32-bits version and also 64-bits , in my honest opinion this shows my friend’s explanation is wrong because all these CPUs are still called the 80×86 architecture although the bits are difference.
As a follow up, what properties did 80×86 architecture inherited from 8086, why doesn’t Intel just call the CPU 8087 but instead it’s called 80186 , 80286 , 80386 and etc?
The 8085 is very different from the 8086. They have different registers, very different instruction sets, they can address different amounts of memory, they handle interrupts differently, etc etc. And, yes, the 8085 is an 8-bit CPU, while the 8086 is 16-bit.
80×86 (or simply x86) commonly refers to 8086/8088, 80186, 80286, 80386, 80486, Pentium. This architecture, as outlined above, is very different from that of 8085/8080 (and quite similar, but more powerful Z80). Why would one want to name entirely different things with the same name?
The 8087 is not a CPU, it’s an FPU. It’s completely different from the 8086. It became a functional part of the 80486 CPU, however. Before then it was an optional PC part. There were multiple FPUs in the series, e.g.: 8087, 80287, 80387. And that’s known as x87.
Today’s x86 CPUs functionally can do all the same things as the 8086, only much faster and they don’t carry some of the 8086 bugs. There are very few things that Intel/AMD don’t want to continue supporting or already chose not to (e.g. undocumented and duplicate instructions and some instructions and instruction encodings in 64-bit mode, but 64-bit mode is not your normal x86 and for that reason is commonly referred to as x86/64 or x64).
If you’re asking why the CPU numbering doesn’t appear very sequential (e.g. a better 8086 would’ve been 8087 and then 8088 and 8089), I don’t know. But how important is that, really?