Digital sound source apparatus and external memory cartridge used therefor

An external memory cartridge detachably connected to an information processing unit which comprises a central processing unit for processing information in a digital manner, a first address bus and a first data bus respectively connected to said central processing unit, and a connector connected to said first address bus and said first data bus, said external memory cartridge comprising:

• a semiconductor memory having a data storage area for storing quantized data in a predetermined address space and a data storage area storing program data for reading and controlling at least the quantized data in response to access from said central processing unit, said semiconductor memory storing a plurality of quantized data for generating a series of sounds as a quantized data train and a stop code in a last address of the quantized data train in said quantized data storage area, and start address data for designating a start address of the quantized data train in a certain address in said program data storage area;
• a printed circuit board attachable to or detachable from said connector, said printed circuit board being formed with a plurality of terminal portions which are connected to said first address bus and said first data bus when the external memory cartridge is inserted into the connector, and a second address bus and a second data bus for connecting said first address bus and said first data bus to said semiconductor memory through respective terminal portions;
• temporary storing means mounted on said printed circuit board and connected to said second data bus for temporarily and sequentially storing the quatized data applied from said second data bus sequentially every time a write signal is applied;
• detecting means connected to said second address bus for detecting that the address data applied to said semiconductor memory from said central processing unit designates said quantized data storage area;
• write control means connected to said second data bus for applying said write signal to said temporary storing means in response to an output of said detecting means and for stopping generation of the write signal in response to detection of said stop code;
• and
• digital/analog converting means for sequentially converting the quantized data temporarily stored in said temporary storing means into an analog signal and outputting the analog signal through said terminal portions on said printed circuit board.