alt Hacker NewsApple managed to design its own state-of-the-art CPUs. I wouldn't have imagined that designing its own modem would be such a difficult challenge?
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The original M-series chip team left years ago, or at least the major drivers. Also: radios are hard, super hard.
CPUs can be easily developed in an ecosystem where annual updates and the ability to end-of-life hardware older than a decade are the norm. Cellular network opereators share none of those properties with Apple, and so any new modem chip designed to interoperate with carriers would necessarily be an order of magnitude more difficult to implement than an CPU that only needs to interoperate with Xcode would be.
Except making a decent modem is indeed harder than start of art CPU. People loves to shit on Qualcomm but dont appreciate that amount of work involved.
The CPU/SOC operates independently with limited protocols (such as PCIe, NVMe, etc.). In contrast, a baseband processor must communicate with various base stations and core networks, requiring precise timing, physical signal alignment, and correct message formats. Even though the 3GPP defines mobile network standards, achieving full compatibility remains extremely challenging.
In fairness, Apple started by licensing the ARM core which gave them a base to work from. The modem is fantastically harder unless you can license an existing design that's not qualcomm.
M chips are ARM so while they designed their particular architecture for it they were still building on some pretty solid foundations.
A modem, well nobody's going to help them build one of those; it'd put them out of business - ARM's business _is_ selling access to its body of work.
One difficult I remember reading is: they can't always do things an obvious way someone else did because... patents.
Their first CPU was launched in 2010, and development likely began in 2006-2007. The M1 launched to much fanfare in 2020.
Their CPU is based on ARM IP, it’s not like they designed it from the ground up. The modem they might have had to? Also I guess a big challenge are all the patents you need to be aware of and find ways to license or circumvent, not sure if that’s worse for modems but it seems all wireless / cellular technology is riddled with patents (not saying CPUs aren’t but again ARM is probably taking care of some of that for Apple).
Modems are harder to get right than CPUs. A CPU needs to do math and work with digital data lines. A modem needs to talk to the mobile network, using radios, and a bunch of standards that were built up since the 90s.