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The answer to this is essentially that CPUs are only cheap if you make them in huge volume, and "I want something that's like a PC but not actually PC compatibl
by pm215 4y ago
The answer to this is essentially that CPUs are only cheap if you make them in huge volume, and "I want something that's like a PC but not actually PC compatible" is a pretty small market, so an SoC designed and manufactured for that niche would just be too expensive for anybody to buy. So if you try to target that niche you are going to be doing it with an SoC designed for some other market, and accepting the tradeoffs that come with it. The traditional high-volume Arm CPU market is mobile, which is what almost all these SBCs are borrowing parts from, and you don't have PCIe on a mobile phone, so no PCIe on an SBC using a mobile part. Possibly as more Arm server chips appear something usable in a desktop form factor will appear, but I suspect that you'll end up just seeing a different set of tradeoffs instead (e.g. much higher price per part).
- throwaway894345 4y agoUnless I'm missing something, an ARM CPU is a PC in every interesting respect. I doubt a SATA, PCIe, USB, etc device cares whether the chip is ARM or x86. So compatibility with the CPU ecosystem doesn't seem like a very compelling reason for low demand. And I would think the M1 proves that there is demand for ARM CPUs (or at least fast, low-power chips). Even if there is some constraint that prohibits scaling up ARM CPUs (e.g., fab capacity shortage) and thus we need to stick with mobile components, what's stopping someone from selling mobos for mobile chips? If the answer is "mobile chips have to be industrially attached to a board" then why aren't there SBCs that are a drop-in replacement for a PC mobo+x86-chip (or if these exist, why are they so niche)?
- pm215 4y agoIt's not a PC in the very important "just boots Windows and runs my existing software" respect. That is what the overwhelming majority of purchasers in the "desktop PC box" market have as an absolute non-negotiable requirement. If you are not an x86 PC compatible, then you're in the really small niche. You could in theory, yes, do a PC-mobo form factor SBC. But no PCI, no SATA, no external DRAM: it doesn't look very much like a PC even if you've stuck it in a PC case...
- throwaway894345 4y agoEh, that's a transient concern. Seems like M1 is going to force the entire ecosystem to support ARM sooner or later (laptop manufacturers are going to start supporting ARM to keep up with Apple, and the software will have to follow suit). Windows and Office already support ARM. > But no PCI, no SATA, no external DRAM Why not? Do mobile ARM chips not support those things? I know the RPI compute modules have PCIe.
- djur 4y agoWhether or not it's a transient concern, manufacturers operate in the market that currently exists, not the one that may exist in the future, and the market that currently exists doesn't include a lot of demand for non-Apple ARM PCs.
- throwaway894345 4y agoI’m asking why the market is as it is, and you’re effectively answering with “because it is”.
- wyldfire 4y agoWindows runs fine on at least a few ARM SoCs and I'm sure most have no SATA. Maybe some have PCIe or at least NVMe. BTW, they were available commercially prior to M1 Macbooks. The vast, vast majority of software written for Windows doesn't care about those buses. And emulation allows for the x86 programs to run without being rebuilt. Windows' biggest drawback in this regard is that hobbyist/enthusiasts generally can't add support for any-old-board. You've got to be a vendor who is willing to get in touch with Microsoft to make it happen.