CD drive



Or "CD drive". The part that fails before everything else in CD systems. Also see optical pickups.

The NeoGeo CD top-loading model drive was made by Sony. The CDZ one was made by Sharp ?

It is made of:
 * A 4-bit MPU (CXP5084), taking care of sequencing and communication (command execution and status report)
 * A DSP (CXD2500) to process analog data from the pickup
 * A servo controler (CXA1372) to drive the pickup coils for tracking and focus
 * A spindle motor driver (Rohm BA6396)

Communication
Some say the protocol was "standard" for the time, but clear information is hard to find. This was guessed from the system ROM disassembly and confirmed with a logic analyzer.

Mobo connector pinout:


 * 1 CDCK (CD drive clock output)
 * 2 High (?)
 * 3 IRQ (output)
 * 4 High (?)
 * 5 HOCK (Host clock input)
 * 6 D0
 * 7 D1
 * 8 D2
 * 9 D3
 * 10 ?
 * 11 2.12MHz ? BCLK ?
 * 12 SDATA
 * 13 LRCK (for audio)
 * 14 High (Mute ?)
 * 15 Ground
 * 16 Logic power (5V)
 * 17 Motor power (voltage ?)
 * 18 Ground

Some signal has to be "D/M", an output which indicates if SDATA is audio or data.

Done through NEO-MGA on a 4-bit bi-directional bus.



More infos to come...

Adjustments
To do !