Display interface uses the ICM7218A/B with an 8048 family microcontroller. The 8-bit data bus (DBO/ DB7-IDO/ID7) transfers control and data information to the 7218 display interface on successive WRITE pulses. The mode input pins on the microcontroller. When mode is high, a control word is transferred; when mode is low, data is transferred. Sequential locations in the 8-byte static memory are automatically loaded on each successive WRITE pulse.
After eight WRITE pulses have occurred, further pulses are ignored until a new control word is transferred.