This is the MZ-700's Programmable Interval Timer ( PIT ). It generates the sound ( 1 voice ) and the 1-second-pulses for a 12- / 24-hours clock.

PIT 8253
Circuit diagram and motherboard mark: AG
MZ-700 SHARP Service Manual info:

Download 8253 technical data sheet ( PDF, 135 KB )

Read the General Overview of the PIT 8253

Read details about the scope of the 8253 in the MZ-700 ( sound, clock- / hardware-interrupt )

Read details about the sound functions of the 8253

Read internals about the sound functions of the 8253