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What is faster, 6502, 6805(HC05) or 8051 ?

Fastest 8-bit CPU ?

  • 6502

    Votes: 0 0.0%
  • 6805(HC05)

    Votes: 0 0.0%
  • 8051

    Votes: 0 0.0%

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Full Member level 3
May 26, 2005
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8051 versus 6805 comparison

From a purely performance point of view, which of these devices you think is a faster 8-bit core ?

• 6502
• 6805 (HC05)
• 8051

Has anyone any comparison benchmark results for these cpus ?

... we've used 32-bit cpus all our lives here...

8051 vs. 6502

"Speed" in processors is a highly volatile and imaginary thing.

Just think of it: a modern PC with multigigabyte 32-bit processor can crunch the immense data stream needed to display a movie; yet it is not fit to control _reliably_ a few simple processes with ms precision, which is a standard task for any 8-bit microcontroller.

Also, it is unfair to compare them without context - development environment (asm or C or other), fulfilled task, development cost, underlying hardware (inside and outside the chip) and possibly a lot of others.

So, at the end of the day, after summing up all the precisely obtained but absolutely useless information you can get from artificial benchmarks, you can conclude only one thing: all these 8-bitters are very similar to each other as per performance under similar conditions. What really counts, is then the personal preference of the user.

My $0.02.


my feeling looking at the ISA and architectures is that they are pretty similar. we will embedded one of this cores in a more complex SoC for some monitor purposes... so we don't care of all the gadgets that come in commercial parts,

we just want to see what is faster as a core.
There are opensource compilers for all of them, although we are not sure about the maturing of each one

> we just want to see what is faster as a core

You apparently did not understand my point.

There is nothing like "faster" in processors; or, it depends on your definition of "faster".

So, define "faster" first.

> There are opensource compilers for all of them

What compiler are you talking about? C? Does this really matter? How do you intend to use it? As a control/monitoring core, it does not need to perform complex tasks, does it? Setting up a couple of registers, sitting in a loop and blinking some LEDs - that's not really a task for which a HLL is necessary. ... What do you mean by "maturity" of a compiler?

Have fun!


Added after 7 minutes:

> my feeling looking at the ISA and
> architectures is that they are pretty similar

One more thing. You might not know the history perhaps - both the 6805 and 6502 originate in Motorola's 6800 and which was a general purpose 8-bit processor. The success of 6502 resulted mostly from the handcrafted design which resulted in a very small transistor count, which was important in times when transistors were large and silicon area was expensive.

On the other hand, 8051 is a completely different story, originating from the 8048, which was a dedicated microcontroller from the onset. There are peculiarities in the '51 - for example the register banks, bit operations - which might make it a bit tougher to implement, but make a small embedded designer's and programmer's life easier.



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