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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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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting SLCReconstructed? Would be interested in seeing what it looks like compared to the real tape.
And while we're at reconstructing... you're wrong about Giana disk orrie, btw. The protection pattern is if I don't remember incorrectly consisting of 128 repeats, not 112.5 or whatever you concluded with (I checked an original dump). Written in speed zone 2 but with a slightly higher RPM than the rest of the floppy.
I am not wrong about it.
Check the document in the website.
From the loader code I got the exact timing range accepted and
re-created a "better" sync which is long exactly at the middle of the range. So my "WP" writes a better more centered one and assures more compatibility with out of speed drives.
About the evil dead reconstruction, I just removed the noise, cleaned up the tap and set all values as they should have been and not as they were read (with the classic +/- 1 variation.
If you are interested I can post it somewhere. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting GroepazQuote:131 * 4 possible parameters cobinations!
so that is the metric for how good the loader is?
Clearly not your judgement. |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting SLCReconstructed? Would be interested in seeing what it looks like compared to the real tape.
https://github.com/Zibri/C64/raw/master/EvilDead_REMASTERED.tap |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:Clearly not your judgement.
i am not judging anything. i am just asking - because the way you brought it up implies its related somehow.
the "judgement" will happen once we can establish some proper metrics and then apply it to different loaders in a systematic way. |
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SLC
Registered: Jan 2002
Posts: 52 |
Quote: Quoting SLCReconstructed? Would be interested in seeing what it looks like compared to the real tape.
https://github.com/Zibri/C64/raw/master/EvilDead_REMASTERED.tap
Why is there jitter in this file? How was it created? |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting SLCWhy is there jitter in this file? How was it created?
There is NO jitter in this file.
Where do you see that?
According to Luigi, the turbo pulses lenghts in Evil Dead were
$17 and $21
I see no value different than those.
Oh.. wait.. if you mean the first turbo pulse, $1A that is a mistake... should be $17 .. my bad.
I just corrected that. |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
TAP-pulse stats:
----------------
$08 : 1
$0f : 1
$17 : 284117
$1a : 191
$1f : 1
$20 : 52
$21 : 148176
$24 : 22
$30 : 41254
$32 : 1
$40 : 169
$42 : 9182
$44 : 9
$56 : 932
$58 : 8
$62 : 1
$a0 : 1
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SLC
Registered: Jan 2002
Posts: 52 |
Quote: Quoting SLCWhy is there jitter in this file? How was it created?
There is NO jitter in this file.
Where do you see that?
According to Luigi, the turbo pulses lenghts in Evil Dead were
$17 and $21
I see no value different than those.
Oh.. wait.. if you mean the first turbo pulse, $1A that is a mistake... should be $17 .. my bad.
I just corrected that.
There is a considerable amount of jitter in both the ROM data and parts of the turbo data. All the way throughout the entire file... |
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Zibri
Account closed
Registered: May 2020
Posts: 304 |
Quoting SLCThere is a considerable amount of jitter in both the ROM data and parts of the turbo data. All the way throughout the entire file...
Rechecked: https://github.com/Zibri/C64/raw/master/EvilDead_REMASTERED.tap
Now it's ok.
P.S.
The presence of A0 08 and 0F is because you are using finaltap which dfoes not understand TAP V1.
those values are inside a long pulse (or silence as many wrongly call it) and not in the real pulses.
In the tap file there are only:
30
42
56
17
21
But in finaltap:
$08 (1) *error*
$0F (1) *error*
$17 (284308)
$21 (148251)
$30 (41256)
$42 (9360)
$56 (940)
$A0 (1) *error* |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
Quote:finaltap
no, not using finaltap. nor is finaltap not understanding tap v1 - it quite correctly identifies the file as such. and if it didnt, it'd show more than one occurance of those values. i guess they come from the long gap at the beginning of the file that shouldnt be there. |
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