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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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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:preferably no bigger than 60 minutes
C30 or C20 actually... which of course are unobtanium these days :) Most important is to use Type-I types though. |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Quote: Quote:preferably no bigger than 60 minutes
C30 or C20 actually... which of course are unobtanium these days :) Most important is to use Type-I types though.
Yes! I remember being able to get dedicated "computer" tapes back in the day of C15 and C20 size.
Anyway, I've been researching these Maxell UE tapes that I have and I think they're counterfeit tapes! No enthusiast circles mention it anywhere (other than the legitimate Maxell UR), and there are no Maxell markings on the tape itself and no labels to apply onto the tape in the case... and yet there are Maxell UEs on ebay with tape labels...
Also I had a second one which I tried and that produced errors even with Gyrospeed when I tried to load it in my other deck, so it's just a BAD fake tape and not worthy of using - and hence shouldn't further influence any reliability tests.
The TDK D seems like the king of Type I cassettes - but while you used to get them dirt cheap, finding them these days is costly - and then there's the risk of ebay knockoffs.
Also tape enthusiasts rave about Sony BHF or HF tapes, and BASF LH-extra I tapes - but I have zero experience with mastering to them, as TDK Ds are the only good tapes I have.
There are also lots of TDK Bs knocking about but many might be fakes. |
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Zibri
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Registered: May 2020
Posts: 304 |
Quoting Neo-Rio
I have a TDK D90, and a Maxell UE 90, and the TDK one allows for high speed mastering. I did all Zibri's testing with the TDK tape.
Just for curiosity (I don't expect "much" difference but some, yes) did you try my tests on the "bad" tape? It would be interesting a comparison on that too. ;) |
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Frantic
Registered: Mar 2003
Posts: 1648 |
Quote: LOL! no, but if you want to come to Sharm El Sheikh I'll show you what a paradise is here :D
A random girl at Twitter just started a thread about "worst place you've travelled to", and her own suggestion was precisely Sharm El Sheikh, which she found really awful. Now of course I realise that people have different tastes, and personally I know nothing at all about Sharm El Sheikh — maybe it is totally great — but it was still kind of funny in relation to this thread. Hehhe..
Aaaanyway... back to topic and keep up the good work on those loaders! I'm eager to see what comes out of it. Maybe I should get myself a datasette again after all, just to be able to load real quick. :D |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Quote: Quoting Neo-Rio
I have a TDK D90, and a Maxell UE 90, and the TDK one allows for high speed mastering. I did all Zibri's testing with the TDK tape.
Just for curiosity (I don't expect "much" difference but some, yes) did you try my tests on the "bad" tape? It would be interesting a comparison on that too. ;)
No I never did any of your tests on the bad tapes. I don't think there'd be much point.
One of the decks had occasional trouble getting to FOUND without distortion creeping in one in every five or so attempts - and that's before it even reached the tape turbo!
I could give it a go anyway, but I would not be expecting miracles! These tapes are only good for people who like their music with snakes hissing as backup singers. :D |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting Neo-RioNo I never did any of your tests on the bad tapes. I don't think there'd be much point.
One of the decks had occasional trouble getting to FOUND without distortion creeping in one in every five or so attempts - and that's before it even reached the tape turbo!
Oh.. then it's very bad, because everything before the lines start is in standard commodore format (like any other normal save)
Also, note, I gave you test files, they have redundant data on them and if you want to compare speeds or counter clicks you should compare from when the "thin" lines start and not before that. In the final version everything before that will be way shorter.
Also note: I made a big calculation error on the last files I gave you. I sent you the updated ones. I was very tired yesterday, it always happens after swimming and taking sun :D
Sorry for wasting some of your time.
And thanks again for the tests. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting FranticA random girl at Twitter just started a thread about "worst place you've travelled to", and her own suggestion was precisely Sharm El Sheikh, which she found really awful. Now of course I realise that people have different tastes, and personally I know nothing at all about Sharm El Sheikh — maybe it is totally great — but it was still kind of funny in relation to this thread. Hehhe..
Yeah.. sure.. I have enought money to live anywhere and I chose the worst place because I am a masochist :D sure.
Many people have horrible holidays here because they go cheap and trust shady travel agencies or go to bad resorts.
I live here full time since 6 years. And it's paradise.
(Unless you like snow, and cold weather, then is hell)
Quote:
Aaaanyway... back to topic and keep up the good work on those loaders! I'm eager to see what comes out of it. Maybe I should get myself a datasette again after all, just to be able to load real quick. :D
ehehe.. the 1541 thanks to the great works of Krill is unbeatable. Internally it uses 26 to 32 microseconds per bit and even considering GCR format that goes at 32.5 to 40 microseconds per bit. That is the equivalent of 25000 to 30769 Hz. which is 3 times what the datassette can handle.
The datassette amplifier has a filter cutting everything above 11Khz (barely detected at 12khz)
An interesting thing of the datassette, anyhow, is that you can directly control it from the C64, while on the 1541 you have to use the IEC bus which is the bottleneck.
Thanks to krill and realtime GCR and 2 bit transfer that is less "felt" but still... |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
While it's relatively easy to align your equipment and master your own tapes for your own use, it's another thing entirely to master a tape with no fancy equipment other than the C2N and then spread warez (lol) to other datasettes - and have the programs load without issue. And then do it on a deck that has probably never been serviced, and has a drive belt that is 30 years old and worn out!
To do this test, I kept the same TDK D90 and had one C2N master the tape, so the other could read it.
Makes absolutely no sense in this day and age to master to garbage tapes for general consumption, and a 90 minute cassette is a borderline length for normal use.
I am simulating the average CBM C2N deck out there and stuck in someone's loft with my CBM deck that has never been serviced, or had it's alignment adjusted. In many ways it is dialing down my test speeds considerably to reach that happy sweet spot where the loader should work on most anything within a user serviceable context.
So my CBM had issues with speeds under 18, and even with 18 had a glitch on loading the very tape it mastered until I tried and second time and it got it right. Interestingly loading the tape on my much newer clone deck presented no issue, but without a doubt, my clone deck is better for making tape masters.
I think Zibri's table is more or less accurate. 18 is the bleeding edge of reliable (if you can tolerate the occasional load failure), 19 may be the sweet spot, and 20 should be rock solid even on a mistreated C2N you found in a car boot sale.
That said, 16 is a reasonably reliable speed for well serviced units and self-made masters you only intend to read for yourself.
According to Zibri and all the dumps I've sent him to analyse, my old CBM deck has a lot of wobble and that's probably down to the worn-out drive belt. I may just hunt down a replacement and see if that helps in the reliability stakes. I guess it makes sense that anyone still using a datasette TODAY get a replacement square belt (75-80mm L x 1-1.2mm W seems to be about the right dimensions), and get rid of any 30 year old belt that's had it's day.
Anyway, we'll see if any improvements need to be made yet, and I'm sure there's more testing to do. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
That brings us back to the question how c2n hardware is specd regarding wow and flutter (wobble) :) |
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Neo-Rio
Account closed
Registered: Jan 2004
Posts: 63 |
Quote: That brings us back to the question how c2n hardware is specd regarding wow and flutter (wobble) :)
And I don't suppose Commodore ever documented this - other than in software?
Software that carried two copies of the data and took forever to load... ?
Did third party software houses ever receive support from Commodore for mastering tapes en masse, or was it simply a wild west? |
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