PC Engine / TurboGrafx 16 CDRom ?

[choijimmy]

Hi,

  I recently got a cdrom
( model CDR-35D-01 -- 2nd item in this link   http://www.pc-engine.co.uk/?section=systems  ).
 It looks like PC Engine / TG-16 cdrom but also look like NEC computer cdrom.

  I plugged into PC Engine interface unit and seems *Not* working with it ( eg, when I press start, No "PC" light show up ).  However, I do know the cdrom works fine because I can play music cd when I press "Play" button on top of the cdrom unit.

Any idea what is it for ?

One more question, is TG-16 cdrom  and PC Engine cdrom interchangeable?

Thanks!

[Keith Courage]

The Black Tg16 CD drive and white pc engine CD drive are interchangeable. I don't know enough about the CDR-35D-01 to know if there is a problem with it or if it just isn't compatible with a pc engine or tg16 setup.

[choijimmy]

Thanks for the info!

[schweaty]

This is just based on memory from a little over 3 years ago, but I believe the NEC computer CDROMs do not work with the pc engine or Turbo CD dock.  They look very similar, but they aren't exactly the same thing.

[choijimmy]

Got it.  Thanks a lot

[gtsamour]

The black and the white CDROM2 units ARE interchangeable and can be used on TG16 dock and on the IFU-30 unit (with the white pce).

I have both and have tried the swaps, they work.

[TailChao]

It is actually possible to use a CDR-35D-01 with a TurboGrafx or PC-Engine, but it requires swapping the drive controller IC (marked D78C14GF) since the drives use different firmware. It's also possible to get an unprogrammed D78C14GF and program it but either way this requires removing a QFP from the board and can be a little difficult without the proper equipment.

[elmer]

It is actually possible to use a CDR-35D-01 with a TurboGrafx or PC-Engine, but it requires swapping the drive controller IC (marked D78C14GF) since the drives use different firmware.

Now that's an obscure and fascinating piece of knowledge! 

I wonder how-on-earth that was discovered. 

[TailChao]

I wonder how-on-earth that was discovered. 

I'm not sure if anyone else has tried the swap, but I only found out because the normal TurboGrafx CD-ROM drives were too expensive but the CDR-35Ds were just cheap enough.

When I got my TurboGrafx it came with the CD booster but no drive or system card and both of those were out of my price range. Almost ten years later I did find a smashed up drive at a flea market but the chips were intact. Since the drives looked so similar I guessed there was only a small change inside and after ordering and disassembling a CDR-35D the boards looked identical and the D78C14GF was suspect since it's a microcontroller with mask rom.

So I swapped the chips and this is how I've been playing CD-ROM games for the past seven years.

[choijimmy]

I wonder how-on-earth that was discovered. 

I'm not sure if anyone else has tried the swap, but I only found out because the normal TurboGrafx CD-ROM drives were too expensive but the CDR-35Ds were just cheap enough.

When I got my TurboGrafx it came with the CD booster but no drive or system card and both of those were out of my price range. Almost ten years later I did find a smashed up drive at a flea market but the chips were intact. Since the drives looked so similar I guessed there was only a small change inside and after ordering and disassembling a CDR-35D the boards looked identical and the D78C14GF was suspect since it's a microcontroller with mask rom.

So I swapped the chips and this is how I've been playing CD-ROM games for the past seven years.

Thanks for the info. I confirmed by swapping D78C14GF  does work!

Indeed, I did swap the D78C14GF with my spare IC few days Before your post. I got a little improvement ( eg, at least I got "PC" LED light when pressing the "start" button" ). However, it still Not able to read the CD games. At that momoent, since I am Not sure this is the RIGHT solution or not. Thus, I gave up.

After reading your post, since I know it is RIGHT solution to swap the IC. I found another spare D78C14GF and this time, it works !!!!  I bet the 1st spare D78C14GF  I tried is defective.

Really appreciate your help.

By the way, any idea how to re-program D78C14GF ( if already programmed ) ?  eg, what kind of equiment?
Thanks!

[TailChao]

Nice, you got it working 

By the way, any idea how to re-program D78C14GF ( if already programmed ) ?  eg, what kind of equiment?

The datasheet mentions a custom programmer from NEC, not sure if anything else supports it. The D78C14s in these drives are likely OTP or mask rom so unfortunately there's no real easy way to reprogram them.

[esteban]

*tech gurus sharing knowledge*

ASIDE: Do you think hardcore NEC PC fans* would shake their heads in disapproval for sacrificing CD-ROM drives for a mere PCE/TG-16 console?

PCE is worth it, of course


*I have no idea if such a person/community exists.

[TailChao]

ASIDE: Do you think hardcore NEC PC fans* would shake their heads in disapproval for sacrificing CD-ROM drives for a mere PCE/TG-16 console?

Probably not, they're just 1x SCSI drives and there's plenty of (better) alternatives in that category.

[esteban]

ASIDE: Do you think hardcore NEC PC fans* would shake their heads in disapproval for sacrificing CD-ROM drives for a mere PCE/TG-16 console?

Probably not, they're just 1x SCSI drives and there's plenty of (better) alternatives in that category.

Thanks for the info.



And now I know that the balance of the cosmos will not be thrown off by CD-ROM drives joining the PCE family.