That or it's the luckiest coincidence! In all seriousness, Apple is fairly consistent about not pushing specs that don't matter and >256GB is just unnecessary for most other common workloads. Factors like memory bandwidth, core count and consumption/heat would have higher impact.
That said, I doubt it was explicitly for R1, but rather based the industry a few years ago when GPT 3s 170B was SOTA, but the industry was still looking larger. "As much memory as possible" is the name of the game for AI in a way that's not true for other workloads. It may not be true for AI forever either.
The high end Intel Macs supported over a TB of RAM, over 5 years ago. It's kinda crazy Apple's own high end chips didn't support more RAM. Also, the LLM use case isn't new... Though DeepSeek itself may be. RAM requirements always go up.
Just to clarify. There is an important difference between unified memory, meaning accessible by both CPU and GPU, and regular RAM that is only accessible by CPU.
As mentioned elsewhere in this thread, unified memory has existed long before Apple released the M1 CPU, and in fact many Intel processors that Apple used before supported it (though the Mac pros that supported 1.5TB of RAM did not, as they did not have integrated graphics).
The presence of unified memory does not necessarily make a system better. It’s a trade off: the M-series systems have high memory bandwidth thanks to the large number of memory channels, and the integrated GPUs are faster than most others. But you can’t swap in a faster GPU, and when using large LLMs even a Mac Studio is quite slow compared to using discrete GPUs.
That said, I doubt it was explicitly for R1, but rather based the industry a few years ago when GPT 3s 170B was SOTA, but the industry was still looking larger. "As much memory as possible" is the name of the game for AI in a way that's not true for other workloads. It may not be true for AI forever either.