CD drive

File:Cd2 cdboard1.jpg

CD2 CD drive board.

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 maskROM MCU (Sony CXP5084), taking care of sequencing and communication (command execution and status report).
• A DSP (Sony CXD2500) to process analog data from the pickup.
• A servo controler (Sony CXA1372) to drive the pickup coils for tracking and focus.
• A spindle and sled 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 a logic analyzer.

Connector pinout, directions are from CDD (CD Drive) to CDC (CD Controller):

Pin #	Name	Type	Direction	Description
1	CDCK	Clock	Output	Tells the CDC when to change HOCK
2	?	?	?	High ?
3	/IRQ	Signal	Output	Asks the CDC for a data exchange (low pulse at ~64Hz)
4	?	?	?	High ?
5	HOCK	Clock	Input	Tells the CDD data is ready on D0~3
6	D0~3	Data	Both	4-bit data bus
7
8
9
10	?	?	?	?
11	BCLK?	Clock	Output	I2S bit clock, should be 44100 * 32 = 1.4112MHz
12	SDATA	Data	Output	I2S data
13	LRCK	Signal	Output	I2S word clock, should be 44100Hz. Audio L/R switch for the DAC.
14	MUTE?	Signal	Input	Put low to gate SDATA ?
15	GND	Power	-	Ground
16	5V	Power	-	+5V for logic
17	9V	Power	-	+9V for motors and coils
18	GND	Power	-	Ground

Some signal has to be "D/M", an output which indicates if SDATA is audio or data. There's a /RESET somewhere also.

NEO-MGA takes care of the I/Os through registers {{Reg|REG.

Adjustments

To do !