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Comment by snvzz | Hacker News Reader

The take-home, IMO:

>Let’s step back for a moment and reflect on what an amazing accomplishment this was. The entire ARM design team consisted of Sophie Wilson, Steve Furber, a couple of additional chip designers, and a four-person team writing testing and verification software. This new 32-bit CPU based on an advanced RISC design was created by fewer than 10 people, and it worked correctly the first time. In contrast, National Semiconductor was up to the 10th revision of the 32016 and was still finding bugs.

Remember: Complexity is poisonous.

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Indeed. And I was also impressed by this:

> Because of the simplicity of the design and the low clock rate, the actual power draw ended up at 0.1 watts.

> In fact, one of the first test boards the team plugged the ARM into had a broken connection and was not attached to any power at all. It was a big surprise when they found the fault because the CPU had been working the whole time. It had turned on just from electrical leakage coming from the support chips.

> This new 32-bit CPU based on an advanced RISC design was created by fewer than 10 people

A small motivated team with sufficient domain knowledge will always outperform large teams, regardless of funding.

The history of business is full of examples of this. Not to go too far, the entire consumer computer industry came out of places like Apple (1 engineer!), Microsoft (a couple of guys), Compaq (three guys), etc.

More perspective on the 32016 vs. the ARM1:

There were about 25K transistors total, in the KISS-or-die ARM1 chip ( https://www.theregister.com/2015/11/28/arm1_visualized/ ).

vs.

There were about 60K transistors in the NS32016 chip, which had to implement features like virtual memory ( http://cpu-ns32k.net/CPUs.html ).

A quote on the 32016, from the latter source: "It is one thing to define a superior architecture on paper. But it is another thing to implement all the required functionality with a limited budget of time and man power." Sounds like NS was really skimping on resources for the 32016. (Wikipedia claims NS had $1 billion in annual sales by 1981, which was Serious Money back then. Vs. the article makes it pretty clear how much leaner things were at Acorn Computer.)

The big difference of course is tooling (CAD tooling) ten years after that I was knocking out that many timed gates a year myself, 5 years later, maybe 5 times more again - that world has changed a lot from the 6502 which was done with litho and modelling knives

Entirely different market 320xx vs ARM (at the time and even now). The simplicity you're advocating as successful for ARM was not applicable for the market NSC was attempting to compete in.

The 320xx, like the 68k, was targeting the nascent Unix workstation market and minicomputer-competition. It was explicitly VAX like -- except simplified (apparently 32xx was quite a clean and consistent architecture). As others have pointed out, it supported everything needed for virtual memory (better than the 68k, actually)

I am not sure ARMv1 (and v2) even had supervisor vs user mode, etc.? (It may have, Google isn't helping me here)

Eventually the 68k ended up in consumer microcomputers (Amiga, Atari ST, etc.) but it started out in that same market. People who wanted to take a bite out of VAX's lunch (which was big money back then.)

The ARM was built by a microcomputer company, for the next generation of their microcomputers. And then for the nest 30 years it was used in various forms for embedded and portable / low-power systems (apart from the ill-fated Archimedes line which was kind of Atari/Amiga/Mac level competition) . It's only in the last few years that we're seeing it in server and workstation class systems.

Note that Apple was an investor and user in ARM from the very earliest days but only in the last couple of years has seen it wise to put it into that class of machine. They went from 68k to PowerPC, and from PowerPC to Intel without choosing ARM for the job, even though they were already a huge ARM customer and had already ported their OS.

Different market, different kind of project.

> I am not sure ARMv1 (and v2) even had supervisor vs user mode, etc.? (It may have, Google isn't helping me here)

v2 at least had 4 modes: user mode, supervisor, IRQ and FIQ. They were encoded in the low 2 bits of r15 (which weren't otherwise needed, since the PC was always word-aligned).

The original Archimedes was intended to run a "preemptively multi tasking, multi-threaded, multi-user, written in Acorn-extended Modula2+" system called ARX. But when that wasn't ready in time, they ended up just porting the 8-bit BBC Micro MOS to the new 32-bit machines!

This is a great read about it all:

http://www.rougol.jellybaby.net/meetings/2012/PaulFellows/in...

This is a great link. Really liked the section

> Now, the aforementioned, Arthur Norman, who had written the LISP interpreter for the BBC Micro, and was in and out of Acorn the whole time, had come up with a design for a machine with 3 instructions called the SKI machine. Whose instructions were called 'S', 'K' and 'I' and it ran LISP in hardware and he built one of these things, it never worked, it was so big and covered in wire-wrap it was always broken. The idea was to prove that you really didn't need very many instructions for a general purpose machine.

https://dl.acm.org/doi/pdf/10.1145/800087.802798

Thanks!

Apple didn't invest in ARM until late 1990, after ARM3 had been released.

By this point Acorn had already released two generations of its UNIX workstation line running its 4.3BSD + X11 based RISC iX, the ARM2 A440/1 based R140 and ARM3 A540 based R260.

It did have virtual memory though its large for the time 32k page size was awkward. It only supported DMA for video so the CPU needed to manually copy data from the hard drive controller.

https://en.wikipedia.org/wiki/RISC_iX

I'll take your word for it on investment date. But Apple used the ARM as early as 1992 (for the Newton). And so, pipeline wise, on their radar much earlier than that. So years before the 68k->PowerPC transition, and while they were still considering 88k.

It is somewhat fun to imagine an alternate world where Apple jumped to ARM instead of PowerPC, but they had other goals at the time. (Likely the whole 68k emulation story would have been very tricky with ARM at the time, tho)

Apple's investment in ARM in November 1990 (when ARM was spun out of Acorn as a joint venture between Acorn, Apple, and VLSI) was a result of Apple's decision to select ARM for the Newton sometime in 1990 since Acorn and Apple competed in the UK education market [1].

[1] https://www.youtube.com/watch?v=_6sh097Dk5k, "A History of The ARM Microprocessor"

Apple can use Arm today because TSMC offers leading edge fabrication. It almost certainly couldn't do before because it would have had to use an uncompetitive node the compared to say Intel.

Plus Apple now has the cash and design team to design a very high performance implementation. It's not had that at the time of the last two transitions.

Had the StrongARM processor come out a little earlier you could just about imagine an alternative where Apple had picked it over the PowerPC. DEC released the StrongARM in 1996 and it was faster and far lower power than Intel's Pentiums of the time.

The StrongARM IP ended up with Intel as XScale when they bought out DEC's semiconductor manufacturing operations as part of a legal settlement. But the lead of Digital's design center that built StrongARM went on to form PA Semi, who Apple bought in 2008. The first Apple-designed ARM chip was released a couple of years later with the iPhone 4 in 2010.

Apple is using ARMv8 which doesn’t have much in common with older ARMs past the name.

Also, Apple didn’t just fund and design a good implementation, ARMv8 was created for the project in the first place.

Source?

https://twitter.com/stuntpants/status/1346470705446092811

That might be the perception inside Apple but I'm certain Arm was planning to build a 64 bit core anyway and would expect to work with leading customers on its development. So calling it 'the Apple ISA' is overstating it a bit.

Also

https://twitter.com/TheKanter/status/1346480394057650177?s=2...

Also it's interesting that when the first Armv8 CPU came out there wasn't any mention by Apple of it being made for them - which is odd given how much weight they give to Apple's input and control elsewhere.

I think the TSCM change is more relevant. Having the best process node in the world for rent for anyone willing to pay is really transformative.

> Entirely different market 320xx vs ARM (at the time and even now). The simplicity you're advocating as successful for ARM was not applicable for the market NSC was attempting to compete in.

Except the original IBM 801 RISC was built - with c20 people - explicitly to compete with VAX. The next set of RISC machines likewise had small teams and high performance.

The whole 32016 approach was just less effective both from design and performance perspective.

Clearly the 32016 was a failure for all sorts of reasons that are well known. The chip was buggy as hell and late.

But it came out around the same time period as the 68000 -- a very similar chip -- which is no less complicated. And that processor was enormously successful. (From what I've seen of the NS32k it was basically... A lot like 68k but little endian and witha smaller register set that wasn't split into address vs data registers)

My point is that 'engineering complexity' can be measured in all sorts of ways. It took 15 years after that period for RISC to truly prove its way, and even then it's been heavily modified from the original "recipe."

But the 68000 dates from 1979 before even the first RISC architectures made to market. Competition was 8088. SGI for example dropped 68k range in due course for MIPS.

What makes ARM interesting to me is that it applied RISC principles in a way that worked well for lower cost computers.

Incidentally you might enjoy this from 1986. They were having the same debates back then as we are now!

https://www.youtube.com/watch?v=DIccm7H3OA0

Definitely agree.

I think the problem is that it’s usually easier to arrive at complex solution than a simple one.

Always work with the following in mind:

Il semble que la perfection soit atteinte non quand il n'y a plus rien à ajouter, mais quand il n'y a plus rien à retrancher.

It seems that perfection is attained not when there is nothing more to add, but when there is nothing more to remove.

Saint-Exupery?

Indeed.

Wind, Sand and Stars just may be my 'Desert Island Book'. Probably not as well known in the English speaking world as it deserves to be.

Perhaps this was simply because the National Semiconductor people were allowed to make mistakes, whereas for ARM it was crucial to get it right the first time.

It also tells that designing hardware is perhaps not as hard as most software engineers make it out to be.

As the article notes, the ARM v1 CPU had 27,000 transistors.

Designing a RISC processor that small is hard in a different way. It’s probably similar to designing a useful CAD application whose code fits in 30 kilobytes on an operating system which only provides file I/O. (That would be the original AutoCAD.)

The difficulty of both hardware and software has changed towards dependency management rather than squeezing the most out of a handful of transistors or program bytes. There’s no reason for anyone to create ARM v1 or AutoCAD 1.0 today.

Agree 100% with the thrust of your argument but isn't the challenge still there today for a Cortex-M0 equivalent say?

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