Which type of RAM is known for needing to be refreshed by an electrical charge?

Synchronous Dynamic RAM (SDRAM) is recognized for its need to be refreshed by an electrical charge. This type of RAM utilizes a dynamic memory mechanism, which means that it stores data in cells made up of capacitors and transistors. Due to the nature of capacitors, the stored information can leak away over time; hence, the data must be refreshed periodically to maintain its integrity. SDRAM is synchronous because it operates in sync with the system clock, allowing it to read and write data on the rising edge of the clock signal. This synchronization improves performance compared to previous generations of RAM.

In contrast, non-volatile RAM retains data without power, making it unnecessary to refresh regularly. Read-Only Memory (ROM) is designed to store permanent data and does not require refreshing as it is not constantly changing. Flash RAM, similar to non-volatile memory, retains data without power and does not need refreshing either. Therefore, SDRAM stands out as the option that clearly requires refreshing due to its reliance on capacitive storage of data.