How much external memory can be connected to the H8S/21xx devices ?
All of the H8S/21xx Series of devices have a 16 Mbyte Linear Addressing Range. Due to the constraints pin count ONLY the H8S/214x Series has all the required address lines A0 - A23 to enable addressing to the full 16 Mbyte. The H8S/213x + H8S/212x Series are limited to a 64 kbtyte addressing range as only address pins A0 - A15 are brought out to the external device pins. In addition only the H8S/214x Series has data lines D0 - D15 available to connect external memory devices. The H8S/213x + H8S/212x series have D0 - D7 available for connecting external memory devices.