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Comment by chasil | Hacker News Reader

The VAX was a 32-bit CPU with an mmu, the 286 was not. UNIX variants on the 286 had severe limitations (64k max program size). VMS was built for a much bigger machine than a 286.

The fab was also in-house.

"It is DEC's first single-chip microprocessor implementation of the VAX ISA and DEC's first self-fabricated microprocessor...

"The MicroVAX 78032 contains 125,000 transistors on an 8.7 by 8.6 mm (74.82 mm2) die that was fabricated in DEC's ZMOS process, a 3.0 µm NMOS logic process with two layers of aluminum interconnect."

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Yes my first reaction was that the VAX would have been a much better architecture but Intel's manufacturing lead meant that it could churn out 286s (and of course 386s in 1985) at much lower cost.

Interesting to compare them both with the ARM1 which was 32 bit (no MMU) but only used 25k transistors on a 3 µm process - and which was more powerful than VAX 11/780. So both powerful and cheap to make.

I really don't understand why Acorn wasn't purchased outright as soon as the samples were back from the fab.

I think DEC was the first third-party implementation with StrongARM.

https://en.m.wikipedia.org/wiki/StrongARM

Yes I think you're right on StrongARM which was the most powerful ARM CPU for a long time. Eventually made its way to Intel I think.

I think everyone eventually had their own RISC - IBM, HP, AMD, Intel (i960) plus MIPs and SPARC of course and a few others.

Arm eventually got traction because of the business model and because they intentionally didn't go head to head with the Intel x86 juggernaut. It wasn't obvious for a long time that their model would work though.

IIRC, StrongARM was the basis for XScale, which Intel foolishly spun off. They could have had a good chunk of the smartphone market, or at least a viable path into it.

Indeed, sold c2006 I think just before the iPhone launched!

But they couldn't have because if they kept XScale they wouldn't have invested in it.

Your comment reminded me of Paul DeMone's signature line on USENET's comp.arch back in the day!

The 801 experiment SPARCed an ARMs race of EPIC proportions to put more PRECISION and POWER into architectures with MIPSed results but ALPHA's well that ends well.

Very good! Just need to get RISC-V in there now too.

"Something, something, RISC-V business"?

> StrongARM which was the most powerful ARM CPU for a long time. Eventually made its way to Intel I think.

DEC sued Intel for patent violations and won. Digital was dying, and part of the settlement was that Intel purchase the billion dollar chip fab in Hudson, Massachusetts that was just built to produce the chips, and later demolished it in 2015.

Interesting thanks.

The 286 was a curious little beast. It did have a sort of an MMU, and, according to Wikipedia, The CPU was designed for multi-user systems with multitasking applications…

286 and for that matter even 386 has the segment-based memory protection mechanism that is somewhat reminiscent of Burroughs mainframes, GECOS and maybe AS/400. There are two giant issues with the idea: it does not work that well on 16b word system and it is totally incompatible with what most of existing code written in C expects. So with 386 Intel had combined that mechanism with traditional MMU and somewhat hack-ish method to turn all that of (reportedly because Microsoft wanted that for Windows/386)

A few operating systems, mostly UNIX clones, did exist that specifically took advantage of 286 protected mode. The 286 has user and supervisor modes, and could address up to 16 MB of physical memory. In protected mode it still used 8086 style segmented addressing, but the segments were virtual.

The bittersweet fact is that when the 80386 came out, OS designers dispensed with segmentation altogether, because it was conceptually so much easier to just flatten out a single vast address space.

So despite the fact that i386 was now capable of really useful and intricate segmented memory architecture, it was the unsegmented, flat virtual address space that won the race.

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