CD drive

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Revision as of 23:36, 1 June 2016 by Furrtek (talk | contribs) (Signal infos)
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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.

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

Adjustments

To do !