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Comment by tambourine_man | Hacker News Reader

Honest, tangentially related question from someone unfamiliar with the field:

Why are we still using old 80xx chips in embedded applications? Expired patents? Existing toolchain? Inertia?

It’s hard to believe we couldn’t do better, cheaper and more power efficient solutions with all the tricks we’ve learned in those almost 40 years.

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The core is simple, small, cheap or even free, requires few resources, has plenty of tool support, is well-understood and well-documented, and is easy to debug and deploy. The 8051 is perfectly sufficient for many simple embedded applications that only require an 8-bit micro.

It's the instruction set that has been retained, not the silicon design. The variants these days are more power-efficient and powerful in terms of MIPS and peripherals, and have indeed benefited from years of R&D.

But is a ISA that wasn’t designed for embedded really that well suited for it?

And if the silicon design is new, we are not benefiting all the much from decades of battle testing, right?

I can’t imagine how a clean, embedded first 32bit ISA design wouldn’t be more appropriate.

> But is a ISA that wasn’t designed for embedded really that well suited for it?

But 8051 was designed for embedded:

> The Intel MCS-51 (commonly termed 8051) is a single chip microcontroller (MCU) series developed by Intel in 1980 for use in embedded systems

(wikipedia)

> I can’t imagine how a clean, embedded first 32bit ISA design wouldn’t be more appropriate

I guess we'll see how riscv will develop.

Ah, I didn’t know that. I thought it was a repurposed chip. That makes sense. Thanks for the clarification.

The 8051 was always designed for "embedded". It's a microcontroller. The ISA is nothing like the 8080's.

Yes but it's a bitch to program, multiple memory hierarchies and address spaces (at least 3), only one index register (hard to move stuff), and enough variants that "8051" is more of a species definition than of a particular architecture

(disclaimer: I sell an 8051 based product, have sold them in the past - never again)

It was designed for embedded use.

Well, it's not as if we're using old stock 80xx chips. They're being laid out on modern foundry processes, AFAIK. With that comes most of the power efficiency.

So much about how processor design has evolved isn't about stuff we've learned, it's about how moore's law has allowed us to have more gates for the same cost, and "what is the best use of all these new gates". 8051s are still pretty competitive in their gate count niche.

It's sort of like how MIPS never really got a lot of traction outside of 5ish stage, in order, optional FPU designs. That's ultimately the gate count niche where they're still competitive.

Because it doesn't need to be better.

It's an embedded application - if the core does the job exactly what it is intended to be, why upgrade? What do you expect more from an eth chip when it already provide full 1gbps capabilities? In other words, there is no room to be better. It could be more power efficient but it is alway efficient enough. Also changing the core will cost a huge amount of money as it needs to change the production line.

Using more recent tech such as ARM isn't always cheaper or better.

Probably the same reasons the 6502 core is being used so much.

Well known cores that are proven reliable over several decades, very well documented and seemingly any bugs are known already. Also cheap

That much cheaper than a modern 32 bit ARM?

I imagine it has to deal with encrypted traffic, IPv6 these days, which doesn’t sound fun on 8bit chips.

It seems weird to me, but again, it’s not my field.

Does any one know what is the market share for 6502, 8051 and ARM?

These 8/16bit cores are rarely used for the main function of the device. They often exist as a general purpose controller to glue together random logic. For example, they might implement the logic that makes the LED be blue when the device is on, and flash blue when the power button is held for 3 seconds, and then trigger a power off when held for 10 seconds (or whatever).

They sometimes might even exist along side of a fully 32bit ARM micro.

Yes. If only because ARM cores mean you need to pay a licensing fee, often times, whereas the 8051, 6502, etc, tend to have significantly better royalty agreements (in my understanding). Also, like the other post says, these aren't used for huge computational uses, it's more for really really basic stuff.

You'd be amazed at the amount of chips that have an 8051 in them...

That's a naive statement that presumes the design used today is mostly similar to the 40 year old design.

Even if it was the exact same circuit design, that's only a small part of what makes a processor and negates all of the advancements in chemistry, lithography, engineering, and everything thing else that goes into manufacturing a chip.

It's like saying "why are we still using scissors|staplers|brushed electric motors|internal combustion engines?"

Why are we still using internal combustion engines?

Maybe barely-rivaled energy density, range, reliability or repairability?

Megawatts of charging rate and 300+kWh storage capacity in small and weight efficient format, not to say cheap too for what it does.

What are the viable alternatives for every use case we currently use ICEs for?

Speaking as a member of a 2 electric car family, I can tell you the current EVs are not 100% replacements for ICE vehicles.

200+ mile EVs can easily supplant ICE vehicles in almost all use cases but they're still more expensive than the average selling price of a new car in the US. That says nothing about the used car market.

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