CDTV CD drive replacement ?

[grelbfarlk]

Originally Posted by utri007

Amiga would really need a way to boot from CD.

One problem has been a lack of rommable cd filesystem, but Amiga OS4 classic boot disk has a rommable cd filesystem.

I think I imagined I tried this before but I might be imagining that I thought I tried it. So someone try it.
http://aminet.net/package/disk/cdrom/mountcd

[Pat the Cat]

Pity. Sounded too good to be true.

I did a bit of digging, seems the interface does have a name at least, list of sound cards supplied with MKE compatible drives at the end. I am not saying these will work or will even fit, but they might be worth internet searching on at the very least.

http://www.vogonswiki.com/index.php/Matsushita_MKE

[utri007]

Originally Posted by grelbfarlk

I think I imagined I tried this before but I might be imagining that I thought I tried it. So someone try it.
http://aminet.net/package/disk/cdrom/mountcd

It doesn't work.

1. MountCD command needs to be executed from CLI <- Needs a boot disk.
2. Needs a CacheCDFS wich is not rommable <- Needs a boot disk.

It needs a bootmedia floppy / hard drive, after that it can boot from CD.

We have a rommable cdfs and device driver, we need to way mount CD with kickstart to boot from it.

[Pat the Cat]

I do seem to recall at least one title showing an AmigaDOS console when loading (on a CDTV). Which suggests there is some kind of CD filesystem already embedded in the ROM.

I guess I could set up Remus and have a delve into the A570 ROM. I did boot a hard disk from one, but as you say, a hard disk isn't the same thing as a CD. Also, filesystem may be incompatible with both IDE and SCSI CD drives. For some reason, CBM used a big ROM in the A570 (27400). The acid test would be just fitting a SCSI CD-ROM via a standard SCSI cart and trying to boot from that... might work if the internal CD is disabled, and the extra SCSI drive is set to drive 0.

Backburner project, but I've already committed to measuring the drive at least. Cable seems compatible between A570 and CDTV, but the latter has a couple of extra pins, both grounded, one connected via resistor. Stops easy swapping of the drives, otherwise they look electrically compatible to me. I can't be 100% of that, A570 schematics are scanned pretty rough.

Looks like an A570 drive should work in a CDTV, but not the other way around without a bit of soldering to fool the CDTV drive.

[grelbfarlk]

Originally Posted by utri007

It doesn't work.

1. MountCD command needs to be executed from CLI <- Needs a boot disk.
2. Needs a CacheCDFS wich is not rommable <- Needs a boot disk.

It needs a bootmedia floppy / hard drive, after that it can boot from CD.

We have a rommable cdfs and device driver, we need to way mount CD with kickstart to boot from it.

It doesn't work at all, or you mean it doesn't work for the non-intended use? What I said is that one could put that package on a floppy or an HDD and run it which sounds like it makes the automount and CacheCDFS reset-resident, then it boots from CD.

I know in our hurry go-go lives you want to sprint to your Amiga, palm slam a CD in the drive and boot your Amiga, but sometimes we have to make some compromises in life.

[nogginthenog]

Originally Posted by utri007

It doesn't work.

1. MountCD command needs to be executed from CLI <- Needs a boot disk.
2. Needs a CacheCDFS wich is not rommable <- Needs a boot disk.

It needs a bootmedia floppy / hard drive, after that it can boot from CD.

We have a rommable cdfs and device driver, we need to way mount CD with kickstart to boot from it.

If you use a rommable filesystem your boot disk could be in ROM. There's one here: https://github.com/cnvogelg/romdisk

[Toni Wilen]

Originally Posted by Pat the Cat

Pity. Sounded too good to be true.

I did a bit of digging, seems the interface does have a name at least, list of sound cards supplied with MKE compatible drives at the end. I am not saying these will work or will even fit, but they might be worth internet searching on at the very least.

http://www.vogonswiki.com/index.php/Matsushita_MKE

CDTV drive is manufactured by Matsushita and has very similar command structure (diagnostic command even returns string "MATSHITA0.96" or 0.97) but commands are slightly different and not compatible.It probably is simply older revision of popular CD command set used in PC drives.

[grelbfarlk]

Originally Posted by nogginthenog

If you use a rommable filesystem your boot disk could be in ROM. There's one here: https://github.com/cnvogelg/romdisk

Thanks for the link, neat stuff. Now I regret not buying those Romys when they were avaialable.

[ImmortalA1000]

I wonder if it would be possible to swap out parts with other early CD-ROM drives like laser, electro-mechanical sections, drive motor/spindle assembly or just mechanical parts of tray loading mechanism. It might still be possible to get a CDTV with no working drive back to life sometimes.

You just have to think of the CDTV repairs the same way as with quirky obscure really old classic cars where identical parts can only come from working machines most of the time for success.

[alexh]

Originally Posted by ImmortalA1000

It might still be possible to get a CDTV with no working drive back to life sometimes.

It seems the CDTV CD unit is prone to capacitor failure and that simply replacing the caps on the PCB will bring most back to life.

[ElectroBlaster]

In theory, would it be possible to emulate the drive with some kind kind of custom add-on board?

Either a standalone emulator board or some kind of bridge board that would allow
the fitting of a standard pata cd drive and have everything translated over to the matsushita part?

Thinking way over my head mind! I have no clue where to start.

EDIT: I did find this regarding CDTV drives not reading at all!

https://www.tsb.space/knowledge-base...-discs-repair/

[simon_m74]

[QUOTE=
Either a standalone emulator board or some kind of bridge board that would allow
the fitting of a standard pata cd drive and have everything translated over to the matsushita part?
[/QUOTE]

I think this is well over my head too.... but I WILL try to design one, I`m doing my best to research the CDTV schematics (that I`ll re-draw in Kicad soon) - so if anyone has any suggestions and help to make a `bridgeboard` from CDTV to IDE/SATA CD drive - lets make it happen!
I can also design a fitting kit to add a slot loader (maybe laptop drive?)

[alexh]

You have to start with the I/O to the CDTV CD-ROM drive. (CN9 on Sheet 10 of the CDTV schematics).

Then the Protocol of the CDTV CD-ROM drive. i.e. it's command set and how it maps to the I/O. I would look at the various references for Panasonic/MKE/SLCD CD-ROM drives (CDTV CD-ROM is similar but earlier), the driver for linux, the WinUAE source code for CDTV emulation. Maybe look at the leaked source code for AmigaOS Extended Kickstart CD-ROM driver (it's in a mix of C and assembler but has some comments).

Just start amassing the information in one place to start with.

Once you've collected as much as you can, have a handle on the I/O and protocol you will need a logic analyzer with enough I/O to capture the CDTV I/O traffic. You might get away with 16-channels. Looking at about £150-£200 but you'll get 80% back when you sell. China make cheap clones of the Saleae 16-channel logic analyzer. https://www.ebay.co.uk/itm/252958728577

Write some software to analyse the protocol from the captures. Some of the analysers (e.g. Saleae) have easy to write scripted protocol analyzers.

Confirm what the CDTV does matches your notes on how the protocol works.

Once you're happy try mapping it from CDTV protocol to IDE/ATAPI protocol?

It may be that it is not practical (i.e. one is many times more simple/complex than the other) in a cost effective CPLD/FPGA.

In which case perhaps look at an ODDE (optical disk drive emulator) that you will be able to implement using a cheap SoC like an RPi PICO.

I cannot dedicate the hours required to finish a project like this but I am happy to discuss things. I've got 30 years experience with SoC design.

[Pyromania]

I guess I better cross my fingers and hope that my CDTV CD drive keeps working.

[simon_m74]

@AlexH
Thanks!
I`m going to design my A4000 Checkmate fitting kit first, then this will by my next project.

I`ll keep in touch.