For a major chip announcement, Apple's M1 launch[1] gave us very little on the chip architecture - page size, memory addressing, internal bandwidth, or clock speeds. At one level that makes sense, given that there is nothing to compare the M1 to, except Apple's own A-series chips.
But for those who like to geek out over such details - like me! - their lack is distressing. But the biggest concern for power users is likely to be memory.
Memory
Apple spent a lot of time emphasizing the power of the new M1 chip, but barely mentioned the 16GB memory limitation. What's more, the touted Unified Memory Architecture just means that 16GB is shared between the CPU and graphics.
What is Unified Memory? According to Apple:
[It] means that the GPU and CPU are working over the same memory. Graphics resources, such as textures, images and geometry data, can be shared between the CPU and GPU efficiently, with no overhead, as there's no need to copy data across a PCIe bus.
So the performance is improved over discrete GPUs, but the shared memory may throttle some graphically intense applications. I'll expect the future 16-inch Mac Pro to have a more powerful chip - M2? - and support 64GB or more memory, with or without a discrete GPU.
Since the 13-inch MacBook Pro and the Mini have fans, I doubt the 16GB limit is thermal. Marketecture is my guess.
Cache
The four high performance cores get a respectable 12MB of shared L2 cache. They also sport a 192KB instruction cache and a 128KB data cache.
The four high efficiency cores make do with a shared 4MB L2 cache, a 128KB instruction cache, and a 64KB data cache.
Both sets of cores offer what Apple calls an ultra-wide