What is L1 memory primarily used for?

L1 memory, or Level 1 cache, is located directly on the CPU chip and is the first cache the CPU accesses when it needs to retrieve or store data. It is specifically designed to provide the fastest possible access to frequently used data and instructions, thus enhancing overall CPU performance. This cache memory operates at the same speed as the processor, allowing it to significantly reduce the latency that would occur if the CPU had to access slower levels of memory or external storage.

In contrast, external storage of files pertains to larger capacity storage options like hard drives or SSDs, which are much slower than L1 cache. Network packet storage involves temporary holding of data packets during network transfer, which is unrelated to the CPU's immediate operational needs. Lastly, data backup of the system generally refers to off-site or external storage solutions that preserve data integrity, which is distinct from the high-speed, immediate operation of L1 cache memory.