Spectravideo SVI318/328 Cassette

+-------------+
|1 2 3 4 5 6 7|
+-------------+

7 PIN FEMALE EDGE CONNECTOR at the computer.

Pin	Name	Description
1	12v	Power 100mA
2	CASR	Cassette data read
3	CASW	Cassette data write
4	AUDIO	Cassette audio
5	GND	System ground
6	ME
7	READY	System Ready

Source: [The Hardware Book]