The DS1243Y-120+ is a 64K NV SRAM with Phantom clock in 28 pin EDIP package. The 64K NV SRAM with Phantom clock is a fully static non-volatile RAM (organized as 8192 words by 8 bits) with a built-in real time clock. The DS1243Y has a self-contained lithium energy source and control circuitry which constantly monitors VCC for an out of tolerance condition. When such a condition occurs, lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent corrupted data in both the memory and real time clock. The Phantom clock provides timekeeping information for hundredths of seconds, seconds, minutes, hours, day, date, month and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. The Phantom clock operates in either 24hour or 12hour format with an AM/PM indicator.