In case you don't know, nspire CX II is a calculator made by Texas Instruments released in 2018. It has an ARM926EJ-s processor running at 396MHz, 64MB of LPDDR memory, and 128MB of SPI nand flash. Though this is probably already an overkill for a calculator, but, can we get even faster on this calculator? Of course, it would really mean anything. I don't need that additional performance, overclocking a calculator is just like overclocking anything else, it is just purely for fun. If I do need more performance, I would go and pick up a laptop. Let's get started.
To overclock any modern processor, there are two key parts: clock synthesizer, memory controller. The first one boosts up the clock frequency, and the second controls the memory timing to make sure the memory runs at higher frequency (if you are unable to decouple the memory frequency with core frequency). The TI nspire CX II uses a custom SoC which I don't have any documents. The operating system on the nspire CX II is also locked down to disallow any unsigned binary code execution. So to overclock it, there are three steps, 1. Get the "root priviledge" on the nspire OS, 2. Understand how clock generation works on nspire, 3. Write a program to overclock it.