The MSC1230 is a Bi-CMOS display driver with digital dimming function. It enables switching between 1/3-duty vacuum fluorescent (VF) display tube and universal VF display tube by pin control. The MSC1230 consists of a 112-bit shift register, a 111-bit latch, a 10-bit digital dimming circuit, 37 segment drivers, and 3 grid drivers. The MSC1230 provides an interface with a microcomputer only by three signal lines: *CS, DATA-IN, and CLOCK. By using the chip select function, the DATA-IN and CLOCK signal lines can be shared by other peripheral circuits.