MSX tapes recovery thread | MSX Resource Center (Page 5/5)

Champion (343)

29-11-2017, 20:47

Louthrax: all of the links to your tool seem to have become broken in the time since you posted them. Did it move elsewhere? I was hoping it might contain more exposition on your "different approach".

By Louthrax

Prophet (2436)

29-11-2017, 22:20

TomH wrote:

Louthrax: all of the links to your tool seem to have become broken in the time since you posted them. Did it move elsewhere? I was hoping it might contain more exposition on your "different approach".

Yes, I've moved all of my tools to a way better server here: https://www.louthrax.net/mgr/ (thanks Luppie for the hosting). My CAS conversion tool is based on Goertzel frequency analysis, so it's more sensitive to frequency, rather than "simple" level or amplitude analysis. It also has lots of parameters and might not be super-easy to use, but I managed to recover some tapes with it. Let me know if that works for you (or not), or if you have questions.

By Danjovic

Champion (326)

08-09-2022, 05:11

Hi Louthrax,
Thanks for the SofaCas.
I have found some old tapes and started to work on the backup of some stuff I have written or typed from magazines (everything else is games already backed up all over the internet, lol).
I am still experimenting with the controls to be able to read some data, specially the ones I recorded at 1800 and 2000 bps. Can you explain better what does the parameter quality means? Do you have more documentation on the other parameters too?

Worth to mention: During the recording the first problem I faced was strong hum induced by ground loop noise. I have built a transformer ground loop isolator, but I think they are available by cheap today.

By Louthrax

Prophet (2436)

08-09-2022, 22:09

Hi Danjovic,

It's been a long time since I last had a look at SofaCas

The "quality" parameter should be something like the tolerance SofaCas had about the header, which is used to determine the baudrate of the data following the header.

I'll need to give a look at the source code again to give you a more accurate answer, I'll maybe have some time this week-end.

Waiting for that, you can of course try different values and see what works best. I'd also be volunteer to try the WAVs files which do not work for you if you're OK sharing them somewhere.

Good luck with your preservation project !

Louthrax

By Danjovic

Champion (326)

09-09-2022, 00:58

Thank you Louthrax,

So far I think that one of the main issues I am facing are due to the low output voltage produced by the transformer I am using (15:1 ratio), but I have increased the rate of success by using a gain between 1.5 to 2.0.

Another issue I am facing is due to my 80's setup without disk drives. Many machine language routines were written to be loaded from 0e000h and beyond, and that seems to interfere with the floppy disk subsystem, then it is hard to tell if I am facing a problem with bad recovered data or "bad coded" suff lol!!!

Nevertheless I appreciate the offer for helping me with the wav files. I will check if any game or app that I have here from my old tapes is rare or unlisted. If that is the case and I could not recover then I will ask your help, does that sound good?

By Manuel

Ascended (19315)

09-09-2022, 07:49

Best is to first try to use the wav file recording on the MSX without drives. If it works, the preservation is already okay!

By imulilla

Rookie (23)

09-09-2022, 16:15

Although a wav dump at first sight "loads" does not mean that it is correct, it may have incorrect pulses that would cause code problems or more or less visible corrupted graphics; That is why it is always important, as far as possible, to have the 2 sides of a tape overturned or 2 copies if it was only recorded on one side, to be able to compare at the data level

By Manuel

Ascended (19315)

09-09-2022, 19:31

Agreed!

By Louthrax

Prophet (2436)

10-09-2022, 21:03

Danjovic wrote:

Another issue I am facing is due to my 80's setup without disk drives. Many machine language routines were written to be loaded from 0e000h and beyond, and that seems to interfere with the floppy disk subsystem, then it is hard to tell if I am facing a problem with bad recovered data or "bad coded" suff lol!!!

You can easily test your recovered .CAS files in openMSX by either choosing a MSX machine that does not have a disk drive, or by keeping the Shift key pressed when starting your MSX (the disk driver is ignored and you should have as much memory as on a MSX without floppy drive).

Lots of games trying to access extra memory had issues too at the time, which could often be solved with a magic POKE-1,XX instruction (documentation about that is available somewhere on this site) or by selecting a working MSX model in openMSX.

Danjovic wrote:

Nevertheless I appreciate the offer for helping me with the wav files. I will check if any game or app that I have here from my old tapes is rare or unlisted. If that is the case and I could not recover then I will ask your help, does that sound good?

Yes, I would really enjoy helping you with that