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Zibri
Account closed
Registered: May 2020
Posts: 304 |
New life for your underloved datassette unit :D
The first phase of testing just ended.
(Still in the packaging and refining phase)
But I wish to share with you all my latest accomplishment.
You might want to check this out:
https://twitter.com/zibri/status/1450979434916417540
and this:
https://twitter.com/zibri/status/1450979005117644800
The fastest example (11 kilobit/sec) has the same (or better) error rlsilience as "turbo250" but it is 3 times faster.
The slowest one (8 kilobit/sec) has the same error resilience as the standard commodore slow "save", but it is 100 times faster and twice as fast as turbo250.
;)
Notes:
1) faster speeds are possible if the tape is written with a professional equipment or hi-fi with a stabilized speed and virtually no wobbling.
2) if the tape is emulated (tapuino or similar projects) the speed can go up to 34 kilobit/sec.
3) even with datassette, higher speeds are possible but the highly depend on the status of the tape, the datassette speed and azimuth. |
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SLC
Registered: Jan 2002
Posts: 52 |
While cool, this is not so much about the loader anymore, but the process of writing the tape, not to mention the C2N itself. You should at least be honest enough to mention that :)
If I had a C2N capable of writing the short pulses required for this, I'd be at those speeds too. I was experimenting with write precompensation but lost interest when I realized it wasn't transferrable to other C2Ns so just tweaked a bit more for reliability and left it there. As for a reliability test, I was able to load all 108 test games written to a C90 on one C2N and read on another at an average 7000bit/s (exomized files only) |
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soci
Registered: Sep 2003
Posts: 480 |
Thanks for trying that. I suspected that was the case but couldn't try it at the time. |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Making TAPs that can't be even played back on actual cassette is pretty cool though - if there was some way to master TAPs to CD ROM and to use the rainbow arts CD adapter to play them back digitally and without error! |
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SLC
Registered: Jan 2002
Posts: 52 |
There is. Convert to .wav and burn as audio. Heck, you can even use mp3... |
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Martin Piper
Registered: Nov 2007
Posts: 722 |
A perfectly (very) reliable C2N that's been very well serviced or calibrated really isn't a good test however. It would be much better to use a standardised test that alters the TAP file bytes to introduce controlled errors and then check, under emulation, that the TAP with errors still loads.
I do this with my TapeTool which can read the TAP, add controlled errors of specific magnitudes, then runs the TAP to check for correct load behaviour. The emulator's remote debugger can be used to check for all the memory being loaded correctly, which also serves as an integration test of the block checksum code. |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Oh yeah, I forgot about audiotap.
I think somebody used to sell those cassette adapters with headphone jacks - like what came with the rainbow arts CD - but I don't think we can get them anymore. Shouldn't be too hard to handcraft one if you have the designs though. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting SLCWhile cool, this is not so much about the loader anymore, but the process of writing the tape, not to mention the C2N itself. You should at least be honest enough to mention that :)
What? Sorry, I don't understand what you mean.
The test tap I passed my testers were all writte unsing a STANDARD C2N and read back using the same device.
And those pulses are not as short as I could make them. But it seems that 40 cycles is the minimum gap to use if you want also to write on a C2N. if You use a recorder using a WAV then I can go as little as 24.
Am I missing something?
And I repeat: BOTH the loader AND the writer must be perfect for this to be possible.
What counts more is that I am able to write sucjh a tape now as I could have been able 39 years years ago.
And this was my challenge (with myself).
And the results speak for themselves. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting Martin PiperA perfectly (very) reliable C2N that's been very well serviced or calibrated really isn't a good test however. It would be much better to use a standardised test that alters the TAP file bytes to introduce controlled errors and then check, under emulation, that the TAP with errors still loads.
That's what I did while developing the first version of my turbo.
I added in my encoder the option to randomly cause errors (pulse lenght changes) and that's how I tested the loader.
Then after it was stable and perfect I started the real world tests. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting Neo-RioOh yeah, I forgot about audiotap.
I think somebody used to sell those cassette adapters with headphone jacks - like what came with the rainbow arts CD - but I don't think we can get them anymore. Shouldn't be too hard to handcraft one if you have the designs though.
I have one of those inside one of my datassette.
They are for sale on any chinese website for very little. I found them for sale even here in Egypt.
With those, if well aligned to the datassette head, the limit is "the sky". I think more that 20 kilobit.. haven't tested it yet... Even if it's perfect I didn't finish even the main loader code. I am adding a few options right now :D
But the new world records Flavioweb just did are a very good motivation to go on. |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Quote: Quoting Neo-RioOh yeah, I forgot about audiotap.
I think somebody used to sell those cassette adapters with headphone jacks - like what came with the rainbow arts CD - but I don't think we can get them anymore. Shouldn't be too hard to handcraft one if you have the designs though.
I have one of those inside one of my datassette.
They are for sale on any chinese website for very little. I found them for sale even here in Egypt.
With those, if well aligned to the datassette head, the limit is "the sky". I think more that 20 kilobit.. haven't tested it yet... Even if it's perfect I didn't finish even the main loader code. I am adding a few options right now :D
But the new world records Flavioweb just did are a very good motivation to go on.
The Rainbow arts CD had an actual circuitboard with headphone jack that plugged onto the cassette port edge-connector on the 64.
You're thinking about those car stereo plastic tape adapters with the headphone jack coming out of them so you can plug them into something else, like a CD player or an iphone, to play music in your car.
I suppose it would work just as well, only that you'd probably have to hack a hole for the cable (or lead it out through the datasette hole - only then the tape would be stuck in there. |
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