Yes, it's basically a function prologue/epilogue in a single instruction. In practice any disassembly of an AArch32 program will have loads of these. It saves instruction cycles in most cases.
That wasn't the actual design goal, though: Acorn was trying to get away with not shipping a DMA controller, which was quite expensive kit at the time they were shipping the Archimedes. Having an instruction pair that let you use registers as DMA buffer let them get similar performance and save lots of per-unit cost.
That wasn't the actual design goal, though: Acorn was trying to get away with not shipping a DMA controller, which was quite expensive kit at the time they were shipping the Archimedes. Having an instruction pair that let you use registers as DMA buffer let them get similar performance and save lots of per-unit cost.