To clarify, scalar instructions are instructions that process one data instruction at a time where vector instructions allow the compiler to process multiple data instructions in parallel. Anyone have any better explanations?
Almost. I believe scalar instructions are those that are applied to a single element (e.g. a variable in a single register) at a time. This is contrasted with a vector instruction where a single instruction is applied to a vector with multiple elements (see slide 29). You're always applying a single instruction, but to different numbers of elements. For vector instructions, this is reflected in the single fetch/decode component that fetches one instruction, but multiple ALUs that can execute that instruction on multiple vector elements.