The document summarizes different components of a computer system unit. It discusses the processor, memory, adapter cards, and power supply as the main components inside the system unit case. It also describes the two main types of memory as RAM and ROM. RAM is volatile memory that loses its contents when power is turned off, while ROM is non-volatile and retains data without power. Examples of RAM include SRAM and DRAM, while examples of ROM include PROM and EPROM.