Specs on CD attachment

[theoakwoody]

What did the CD attachment add as far as specs go.  Was it just a player or did it add memory, palette, a sound chip, etc.  Did the cd attachment really add that much other than bigger storage capacity and redbook audio?

[TurboXray]

the original CD unit added:

 Additional 64k of ram - used to hold game data

 Additional 64k of ADPCM ram for ADPCM voice samples( some games stored code and graphics here)

 A BIOS library so you didn't have to include general lib code everytime you load new code( levels) - saved space and made programming easier. Also included pseudo functions like multiply/divide of 16bit numbers, square root, and a lookup table for SIN/COS, etc.

 1x ADPCM voice/effects sample play/funtions ontop of existing PSG sound channels, CD audio play functions, and composite video w/ stereo output.

 The Super CD upgrade added 192k ontop of the existing ram for a total of 256k system ram/64k ADPCM ram.

[theoakwoody]

Was the added 64K for ADPCM just memory or was it another coprocessor?  So if I'm reading your last post correctly the cd attachment didn't add any kind of additional chipset to the machine.

[TurboXray]

The CD attachment didn't add any more chipsets to the system in the way the SegaCD did to the Genesis, although the ADPCM controller was a seperate device - ADPCM didn't use the CPU resource to play the voice/effect samples like the normal PSG sound required. The ADPCM part is made up of 64k of ram and an audio controller/processor.

[theoakwoody]

Have you ever cracked open a cd docking tray to see what it looks like inside.  Is it just the connectors between the cd and the pc engine?

[TurboXray]

I've not opened the original CD unit, but I have opened my duo. The TG/PCE connects to the CDROM via a SCSI interface/controller(well a strip down version) with 8k buffer, not directly to the CDROM unit.

[Joe Redifer]

I have opened the original CD unit to tap RGB video outputs.  It is cram packed with capacitors, resistors, solder, shielding and stuff like that.  I thought it would be mostly empty space.

[theoakwoody]

That's interesting that you tapped the base because isn't it easier to just tap the actual tg16 for rgb or is that not possible with the cd attachment.  I've wanted to do rgb but none of these how-to's show the mod on the cd attachment.

[Joe Redifer]

I didn't feel like drilling a hole in my Turbo and the CD attachment is easier to work with (but still not super easy).