Discussion:
Please test 23k cassette encoding
(too old to reply)
r***@gmail.com
2017-10-22 17:23:47 UTC
Permalink
Raw Message
Hi all,

I've packaged together an easy-to-do test for the 23k encoding I've prototyped and have been discussing here. Just type "LOAD" from the BASIC prompt and play this file into the cassette port:

http://levien.com/23k_test.wav

It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.

Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.

Many thanks,

Raph
James Davis
2017-10-22 18:40:43 UTC
Permalink
Raw Message
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Could you put it in a downloadable zip file?
r***@gmail.com
2017-10-22 19:36:04 UTC
Permalink
Raw Message
Post by James Davis
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Could you put it in a downloadable zip file?
Done: http://levien.com/23k_test.zip
James Davis
2017-10-22 19:57:10 UTC
Permalink
Raw Message
Post by r***@gmail.com
Post by James Davis
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Could you put it in a downloadable zip file?
Done: http://levien.com/23k_test.zip
Thanks.

As soon as I can figure out why I keep getting "Syntax Errors" when trying to "Load" from the Applesoft prompt on my Enhanced Apple //e, I'll let you know what I can about it.
Egan Ford
2017-10-23 15:13:11 UTC
Permalink
Raw Message
Post by James Davis
As soon as I can figure out why I keep getting "Syntax Errors" when trying to "Load" from the Applesoft prompt on my Enhanced Apple //e, I'll let you know what I can about it.
Do not boot an OS. Remove any floppies, power on, ctrl-reset, then LOAD
James Davis
2017-10-23 20:14:38 UTC
Permalink
Raw Message
Post by Egan Ford
Post by James Davis
As soon as I can figure out why I keep getting "Syntax Errors" when trying to "Load" from the Applesoft prompt on my Enhanced Apple //e, I'll let you know what I can about it.
Do not boot an OS. Remove any floppies, power on, ctrl-reset, then LOAD
Problem is, it boots from my Sider in slot-7. I'll have to see if ctrl+reset will drop out of ProSel or just reboot. I'll let you know later.
James Davis
2017-10-24 08:36:02 UTC
Permalink
Raw Message
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Raph,

I got your wave file to load. Took about 5 seconds, counting 1-1000, 2-1000, etc. Final result: a hi-res picture of random dots/dashes of colors/white/black. I did not see two pictures, or if I did, I did not see a change from one to the other, IIRC, but I was not watching very closely.

I used an audio cable from my Lenovo PC to my Enhanced Apple //e. I extracted the 23k_test.wav file from 23k_test.zip using 7-zip. Played the 23k_test.wav file using (default) Windows Media Player. Speaker volume was set to 50% with no enhancements. [This is the same volume that I used to bootstrap ADT ProDOS.]

I had to turn off my Apple //e to get out from under your program and then turn it back on to park my Sider HDD heads. My Apple //e kept dropping into the monitor after escaping your program instead of cold/warm starting when I pressed ctrl+reset or ctrl+apple+reset.

I think it might be easier to see changes if you had two pictures of real things that are different from each other but very recognizable (like your "mug shot," front and profile, with a placard numbered one and two [ ;-) & )-; ], LOL). Then, if there were errors, they would not look as good (as you), full of holes (random dots/dashes of colors/white/black). You could show each picture for a few seconds each, repeatedly until escape is pressed, then exit to Applesoft/Integer BASIC via the cold start entry vector ($E000). [That is what I had to do after booting up ProDOS/ProSel and dropping into Applesoft, then into the Monitor ( ]Call-155 then *E000G ) before I could LOAD successfully. Later, I realized that all I really had to do was to turn off my Sider before turning on my Apple //e.]

James Davis
r***@gmail.com
2017-10-24 16:31:16 UTC
Permalink
Raw Message
Post by James Davis
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Raph,
I got your wave file to load. Took about 5 seconds, counting 1-1000, 2-1000, etc. Final result: a hi-res picture of random dots/dashes of colors/white/black. I did not see two pictures, or if I did, I did not see a change from one to the other, IIRC, but I was not watching very closely.
I used an audio cable from my Lenovo PC to my Enhanced Apple //e. I extracted the 23k_test.wav file from 23k_test.zip using 7-zip. Played the 23k_test.wav file using (default) Windows Media Player. Speaker volume was set to 50% with no enhancements. [This is the same volume that I used to bootstrap ADT ProDOS.]
I had to turn off my Apple //e to get out from under your program and then turn it back on to park my Sider HDD heads. My Apple //e kept dropping into the monitor after escaping your program instead of cold/warm starting when I pressed ctrl+reset or ctrl+apple+reset.
I think it might be easier to see changes if you had two pictures of real things that are different from each other but very recognizable (like your "mug shot," front and profile, with a placard numbered one and two [ ;-) & )-; ], LOL). Then, if there were errors, they would not look as good (as you), full of holes (random dots/dashes of colors/white/black). You could show each picture for a few seconds each, repeatedly until escape is pressed, then exit to Applesoft/Integer BASIC via the cold start entry vector ($E000). [That is what I had to do after booting up ProDOS/ProSel and dropping into Applesoft, then into the Monitor ( ]Call-155 then *E000G ) before I could LOAD successfully. Later, I realized that all I really had to do was to turn off my Sider before turning on my Apple //e.]
James Davis
Thanks, that's at least one data point confirming my suspicion that the encoding is too sensitive to calibration differences.

I've redone the encoding completely, getting rid of the asymmetry, and have samples here:

http://levien.com/20ktest.zip

The encoding is sensitive to polarity, so I've put both polarities in there.

I'm excited about the new encoding, because I think it will be quite robust (probably more so even than the 8k encoding in c2t). I've already confirmed that it can play at 44.1k and 48k sampling rates.

Raph
James Davis
2017-10-24 23:59:16 UTC
Permalink
Raw Message
Post by r***@gmail.com
Post by James Davis
Post by r***@gmail.com
Hi all,
http://levien.com/23k_test.wav
It contains two copies of an image file. If there are bit errors, then you'll see some of the pixels change from the first copy to the second - I see this when the volume is outside the reliable range.
Let me know failure/success, what kind of Apple you have, what your sound output device is, and what range of volumes seem to work.
Many thanks,
Raph
Raph,
I got your wave file to load. Took about 5 seconds, counting 1-1000, 2-1000, etc. Final result: a hi-res picture of random dots/dashes of colors/white/black. I did not see two pictures, or if I did, I did not see a change from one to the other, IIRC, but I was not watching very closely.
I used an audio cable from my Lenovo PC to my Enhanced Apple //e. I extracted the 23k_test.wav file from 23k_test.zip using 7-zip. Played the 23k_test.wav file using (default) Windows Media Player. Speaker volume was set to 50% with no enhancements. [This is the same volume that I used to bootstrap ADT ProDOS.]
I had to turn off my Apple //e to get out from under your program and then turn it back on to park my Sider HDD heads. My Apple //e kept dropping into the monitor after escaping your program instead of cold/warm starting when I pressed ctrl+reset or ctrl+apple+reset.
I think it might be easier to see changes if you had two pictures of real things that are different from each other but very recognizable (like your "mug shot," front and profile, with a placard numbered one and two [ ;-) & )-; ], LOL). Then, if there were errors, they would not look as good (as you), full of holes (random dots/dashes of colors/white/black). You could show each picture for a few seconds each, repeatedly until escape is pressed, then exit to Applesoft/Integer BASIC via the cold start entry vector ($E000). [That is what I had to do after booting up ProDOS/ProSel and dropping into Applesoft, then into the Monitor ( ]Call-155 then *E000G ) before I could LOAD successfully. Later, I realized that all I really had to do was to turn off my Sider before turning on my Apple //e.]
James Davis
Thanks, that's at least one data point confirming my suspicion that the encoding is too sensitive to calibration differences.
http://levien.com/20ktest.zip
The encoding is sensitive to polarity, so I've put both polarities in there.
I'm excited about the new encoding, because I think it will be quite robust (probably more so even than the 8k encoding in c2t). I've already confirmed that it can play at 44.1k and 48k sampling rates.
Raph
Raph,

I have retested with all of your wave files: 23k, 20k & inverse. All were consistently successful at 90% speaker volume, using the same hardware/software as stated before/above in this thread. [I had to turn my Enhanced Apple //e off and on each time between tests. Otherwise, after ctrl+reset, a second LOAD would crash into the monitor (* prompt) and continue to do so, no matter what. You need to write a more turnkey application to prevent this.] I got 10 good clean vertical white bars (and 9 or 10 black bars) across the screen. The outer edges of the white bars had some color fringing (green on right side, cyan on left side, 1 pixel wide, on each bar). At 100% volume, I got some noise. At 75% volume, I got LOAD ERRORS. The 100% volume noise was random color pixels within the vertical bar pattern; mostly confined to three 4-square (2x2) Low-Res block areas within the white bar areas. At 50% volume was my previous un-"successful" tests as described above; but, that was probably because I had booted into ProDOS/ProSel first before restarting Applesoft Cold.

I hope this helps,

James Davis
James Davis
2017-10-25 00:11:11 UTC
Permalink
Raw Message
P.S. So, how is this useful if I have to turn my computer off and on again to do anything else with the computer?
Michael J. Mahon
2017-10-25 00:38:44 UTC
Permalink
Raw Message
Post by James Davis
P.S. So, how is this useful if I have to turn my computer off and on
again to do anything else with the computer?
This is a test. This is *only* a test. ;-)
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
James Davis
2017-10-25 01:23:53 UTC
Permalink
Raw Message
Post by Michael J. Mahon
Post by James Davis
P.S. So, how is this useful if I have to turn my computer off and on
again to do anything else with the computer?
This is a test. This is *only* a test. ;-)
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
Yes, I know, but it would be nice if the test had a proper exit and didn't lock up the computer; e.g., "Press any key" to return to Applesoft/Integer BASIC; so one could LOAD again and again--to test more than once and/or to test more frequencies--without having to power down each time. My switch is pretty old. I don't want to break it.
r***@gmail.com
2017-10-25 03:05:43 UTC
Permalink
Raw Message
Post by James Davis
Post by Michael J. Mahon
Post by James Davis
P.S. So, how is this useful if I have to turn my computer off and on
again to do anything else with the computer?
This is a test. This is *only* a test. ;-)
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
Yes, I know, but it would be nice if the test had a proper exit and didn't lock up the computer; e.g., "Press any key" to return to Applesoft/Integer BASIC; so one could LOAD again and again--to test more than once and/or to test more frequencies--without having to power down each time. My switch is pretty old. I don't want to break it.
Hmm, Ctrl-Openapple-Reset works for me. I could probably tweak the test code to add a proper exit though.

You're not seeing a photo of an Apple computer? That's what you're _supposed_ to see.

Also, do you know if any of the faster c2t modes work for you? So far I've gotten the old (non -96h) 8k mode to work, but none of the others. It's starting to look like there's a wide variation from machine to machine.

Raph
James Davis
2017-10-25 07:01:37 UTC
Permalink
Raw Message
Post by r***@gmail.com
Post by James Davis
Post by Michael J. Mahon
Post by James Davis
P.S. So, how is this useful if I have to turn my computer off and on
again to do anything else with the computer?
This is a test. This is *only* a test. ;-)
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
Yes, I know, but it would be nice if the test had a proper exit and didn't lock up the computer; e.g., "Press any key" to return to Applesoft/Integer BASIC; so one could LOAD again and again--to test more than once and/or to test more frequencies--without having to power down each time. My switch is pretty old. I don't want to break it.
Hmm, Ctrl-Openapple-Reset works for me. I could probably tweak the test code to add a proper exit though.
You're not seeing a photo of an Apple computer? That's what you're _supposed_ to see.
Also, do you know if any of the faster c2t modes work for you? So far I've gotten the old (non -96h) 8k mode to work, but none of the others. It's starting to look like there's a wide variation from machine to machine.
Raph
So, you are saying that what I am seeing is not what I am supposed to be seeing, that my tests have been unsuccessful. Please include a JPEG picture of it in the next zip. CyderPress or Buckshot can convert the Hi-Res picture to a Bitmapped picture, and MS Paint can then save it as a JPG picture. You have got me wondering if there are more things going wrong with my old Apple IIe than just not being able to get ADT ProDOS server to hear the audio cassette output from it. I'll have to see if I have some HI-RES pictures on my HDD that I can view to test that, too. I can't imagine why I would get 10 perfect vertical white stripes instead of a good or bad picture of an Apple II. If I ever get a good result, I'll let you know.
Michael 'AppleWin Debugger Dev'
2017-10-25 17:01:48 UTC
Permalink
Raw Message
Post by James Davis
I think it might be easier to see changes if you had two pictures of real things that are different from each other but very recognizable (like your "mug shot," front and profile, with a placard numbered one and two [ ;-) & )-; ], LOL).
So, you are saying that what I am seeing is not what I am supposed to be seeing, that my tests have been unsuccessful. Please include a JPEG picture of it in the next zip. CyderPress or Buckshot can convert the Hi-Res picture to a Bitmapped picture, and MS Paint can then save it as a JPG picture.
You guys are making this WAY more complicated then necessary.
Clear the HGR screen to a solid color and you can easily tell the order:

; Clear to Green
ORG $300
LDA #2A
STA $1C
LDA #$20
JMP $F3F6

; Clear to Blue
LDA #D5
STA $1C
LDA #$20
JMP $F3F6

; Colors:
; 2A = Green
; 55 = Magenta
; AA = Orange
; D5 = Blue

Hexdump:

300:A9 2A 85 1C A9 20 4C F6 F3
309:A9 D5 85 1C A9 20 4C F6 F3
James Davis
2017-10-25 19:56:43 UTC
Permalink
Raw Message
Post by Michael 'AppleWin Debugger Dev'
Post by James Davis
I think it might be easier to see changes if you had two pictures of real things that are different from each other but very recognizable (like your "mug shot," front and profile, with a placard numbered one and two [ ;-) & )-; ], LOL).
So, you are saying that what I am seeing is not what I am supposed to be seeing, that my tests have been unsuccessful. Please include a JPEG picture of it in the next zip. CyderPress or Buckshot can convert the Hi-Res picture to a Bitmapped picture, and MS Paint can then save it as a JPG picture.
You guys are making this WAY more complicated then necessary.
; Clear to Green
ORG $300
LDA #2A
STA $1C
LDA #$20
JMP $F3F6
; Clear to Blue
LDA #D5
STA $1C
LDA #$20
JMP $F3F6
; 2A = Green
; 55 = Magenta
; AA = Orange
; D5 = Blue
300:A9 2A 85 1C A9 20 4C F6 F3
309:A9 D5 85 1C A9 20 4C F6 F3
Michael: "... [than] necessary." You got it right the other day when you thanked me, but wrong ever since. Please, do not take offense. I know how hard it is to break old habits.

Raph: Does Michael's code help you?

James Davis
Michael 'AppleWin Debugger Dev'
2017-10-25 21:06:45 UTC
Permalink
Raw Message
Post by James Davis
Michael: "... [than] necessary." You got it right the other day when you thanked me, but wrong ever since. Please, do not take offense. I know how hard it is to break old habits.
No worries. No offense taken. That completely slipped under my radar.

I see that this will be my bane until my end of days. :-(
Steve Nickolas
2017-10-27 03:52:07 UTC
Permalink
Raw Message
Post by Michael 'AppleWin Debugger Dev'
Post by James Davis
Michael: "... [than] necessary." You got it right the other day when you thanked me, but wrong ever since. Please, do not take offense. I know how hard it is to break old habits.
No worries. No offense taken. That completely slipped under my radar.
I see that this will be my bane until my end of days. :-(
I have a friend with very precise UK English who nonetheless almost never
spells words with the combination C-E-I correctly. :P

-uso.
Egan Ford
2017-10-25 20:53:41 UTC
Permalink
Raw Message
Post by r***@gmail.com
Also, do you know if any of the faster c2t modes work for you? So far I've gotten the old (non -96h) 8k mode to work, but none of the others. It's starting to look like there's a wide variation from machine to machine.
What are you using to play the audio of the 9.6K mode? Can you try a
different audio player?
r***@gmail.com
2017-10-26 15:24:12 UTC
Permalink
Raw Message
Post by Egan Ford
Post by r***@gmail.com
Also, do you know if any of the faster c2t modes work for you? So far I've gotten the old (non -96h) 8k mode to work, but none of the others. It's starting to look like there's a wide variation from machine to machine.
What are you using to play the audio of the 9.6K mode? Can you try a
different audio player?
I'm using sox directly to the USB audio device (the built-in DAC in the Dell P2715Q monitor). I've used a scope to verify that this is an accurate, high-quality path with no additional effects.

But I do have some more insight into what's going wrong. Both -8 and -f modes (in c2t-96h) work when polarity is inverted (-v -0.5 in sox). This seems to be a characteristic of these fancier sense loops, they're detecting particular transitions rather than flips as in the Apple encoding. I noticed that Jorge's demo has an "invert" button. For me, it worked at the normal setting.

I'm wondering if this might be a systematic reason people have trouble with the faster c2t modes.
James Davis
2017-11-01 00:25:14 UTC
Permalink
Raw Message
So raph, are there any more tests you wand done? What's happened in the last week? Have you made any progress?
r***@gmail.com
2017-11-01 01:15:22 UTC
Permalink
Raw Message
Post by James Davis
So raph, are there any more tests you wand done? What's happened in the last week? Have you made any progress?
I don't have much to show publicly from the last week - I've started integrating the sense code into c2t proper, but it's non-trivial. I'd like to see results from at least one or two other machines - if I can't get this to work on any machine other than the one at Recurse Center, it demotivates me.

One idea I'm toying with is to write a separate standalone utility (shipped as a wav file that you can LOAD) that characterizes the audio connection. My basic idea is to have a sense core that samples a few milliseconds of sound into a small memory buffer, then an analysis pass that basically measures duty cycle and jitter. Then the audio file contains a whole bunch of test tones, including at different amplitudes to test sensitivity to volume.

I'm a bit busy with other things, not sure exactly when this will happen. Thanks for your continued interest.
Michael J. Mahon
2017-11-01 16:11:07 UTC
Permalink
Raw Message
Post by r***@gmail.com
Post by James Davis
So raph, are there any more tests you wand done? What's happened in the
last week? Have you made any progress?
I don't have much to show publicly from the last week - I've started
integrating the sense code into c2t proper, but it's non-trivial. I'd
like to see results from at least one or two other machines - if I can't
get this to work on any machine other than the one at Recurse Center, it demotivates me.
One idea I'm toying with is to write a separate standalone utility
(shipped as a wav file that you can LOAD) that characterizes the audio
connection. My basic idea is to have a sense core that samples a few
milliseconds of sound into a small memory buffer, then an analysis pass
that basically measures duty cycle and jitter. Then the audio file
contains a whole bunch of test tones, including at different amplitudes
to test sensitivity to volume.
I'm a bit busy with other things, not sure exactly when this will happen.
Thanks for your continued interest.
Great idea--actually measuring the cassette input response for a particular
player/computer combo!
--
-michael - NadaNet 3.1 and AppleCrate II: http://michaeljmahon.com
r***@gmail.com
2017-11-20 00:04:09 UTC
Permalink
Raw Message
I've been experimenting and thinking more on this, and my latest thoughts are here:

https://github.com/datajerk/c2t/issues/4

Quick summary: I've identified polarity inversion as a serious problem; I'm trying to figure out how to balance 6502 code size against other factors; and I'm seeking input on whether to try to ship something in the 16kbps range with relatively simple waveform generation (but which would be much more reliable than the 23kpbs prototype I first posted), or whether keep pushing on the engineering to get the speeds high.
Egan Ford
2017-11-21 17:27:19 UTC
Permalink
Raw Message
Post by r***@gmail.com
https://github.com/datajerk/c2t/issues/4
Quick summary: I've identified polarity inversion as a serious problem; I'm trying to figure out how to balance 6502 code size against other factors; and I'm seeking input on whether to try to ship something in the 16kbps range with relatively simple waveform generation (but which would be much more reliable than the 23kpbs prototype I first posted), or whether keep pushing on the engineering to get the speeds high.
I'd start with 16kbps and get as many as possible to test. There is
variation between players and IIs.
b***@gmail.com
2017-10-25 06:14:08 UTC
Permalink
Raw Message
I'm going to test this, it has great interest to me, as my transfers to my Apple are limited to the cassette port, as I do not have a SSC.

Using ADTPro is *painfully* slow, a 40-track disk takes ~10 minutes or longer to transfer over.

If your method, at 23kbit/sec is viable, it will improve this time to under a minute! I anxiously look forward to that day. Your efforts are truly appreciated.

Please excuse my tardiness in testing, as I want to wait until this terrible 105-degree heatwave is over first. Then I'll be able to function and provide you the necessary and proper feedback.
Egan Ford
2017-10-25 21:03:05 UTC
Permalink
Raw Message
Post by b***@gmail.com
I'm going to test this, it has great interest to me, as my transfers to my Apple are limited to the cassette port, as I do not have a SSC.
Using ADTPro is *painfully* slow, a 40-track disk takes ~10 minutes or longer to transfer over.
If your method, at 23kbit/sec is viable, it will improve this time to under a minute! I anxiously look forward to that day. Your efforts are truly appreciated.
Please excuse my tardiness in testing, as I want to wait until this terrible 105-degree heatwave is over first. Then I'll be able to function and provide you the necessary and proper feedback.
Are you transferring Apple II to image or image to Apple II, if the
later, then consider using c2t(-96h) (8000-9600bps). With c2t builtin
compression the effective BPS rate has been measured as high as 40000
bps. The average effective bps rate is 19000 based on 1500
virtualapple.org games.

Effective BPS rate is based on the time to transfer and decompress the
data. Not the time to write to disk.
Jorge
2018-02-10 10:15:58 UTC
Permalink
Raw Message
How is this freaking awesome thing going? Any progress?
STYNX
2018-02-12 11:44:37 UTC
Permalink
Raw Message
Post by Jorge
How is this freaking awesome thing going? Any progress?
Im interested in the result as well. I wonder if acceleration (TW, Zipchip) could allow for more speed?
A high speed LOAD feature via tape interface for ADTpro would be nice :-)

Something like: first load a mini loader over the normal A2 LOAD method and then execute the mini loader for high speed loading...

-Jonas
Jorge
2018-02-12 19:19:43 UTC
Permalink
Raw Message
Post by STYNX
Post by Jorge
How is this freaking awesome thing going? Any progress?
Im interested in the result as well. I wonder if acceleration (TW, Zipchip) could allow for more speed?
A high speed LOAD feature via tape interface for ADTpro would be nice :-)
Something like: first load a mini loader over the normal A2 LOAD method and then execute the mini loader for high speed loading...
The web site of Egan Ford does that already: http://asciiexpress.net/diskserver/ but the audio encoding he's using is not very reliable.

I think a zipchip won't help much because the problem is the audio in hardware of the Apple II and the audio out hardware of a PC/Mac/Phone, more than the speed of the Apple II cpu. The speed limit is around 14 kbps max IMHO.
--
Jorge.
Egan Ford
2018-02-13 03:35:01 UTC
Permalink
Raw Message
Post by Jorge
Post by STYNX
Post by Jorge
How is this freaking awesome thing going? Any progress?
Im interested in the result as well. I wonder if acceleration (TW, Zipchip) could allow for more speed?
A high speed LOAD feature via tape interface for ADTpro would be nice :-)
Something like: first load a mini loader over the normal A2 LOAD method and then execute the mini loader for high speed loading...
The web site of Egan Ford does that already: http://asciiexpress.net/diskserver/ but the audio encoding he's using is not very reliable.
I beg to differ. It is quite reliable. There are a few edge cases with
9600 BPS and older players. 8000 BPS has no known outstanding issues
that I can recall.
Jorge
2018-02-13 10:02:48 UTC
Permalink
Raw Message
Post by Egan Ford
Post by Jorge
The web site of Egan Ford does that already: http://asciiexpress.net/diskserver/ but the audio encoding he's using is not very reliable.
I beg to differ. It is quite reliable. There are a few edge cases with
9600 BPS and older players. 8000 BPS has no known outstanding issues
that I can recall.
Oh, sorry. I say so because it didn't work so well for me. You have to find the proper volume setting and that's very very tricky. As I told you before when it works it's great.
Egan Ford
2018-02-13 21:07:35 UTC
Permalink
Raw Message
Post by Jorge
Post by Egan Ford
Post by Jorge
The web site of Egan Ford does that already: http://asciiexpress.net/diskserver/ but the audio encoding he's using is not very reliable.
I beg to differ. It is quite reliable. There are a few edge cases with
9600 BPS and older players. 8000 BPS has no known outstanding issues
that I can recall.
Oh, sorry. I say so because it didn't work so well for me. You have to find the proper volume setting and that's very very tricky. As I told you before when it works it's great.
AFAIK, for everyone else max volume works.
Jorge
2018-02-14 20:40:16 UTC
Permalink
Raw Message
Post by Egan Ford
Post by Jorge
Oh, sorry. I say so because it didn't work so well for me. You have to find the proper volume setting and that's very very tricky. As I told you before when it works it's great.
AFAIK, for everyone else max volume works.
Sorry, but I doubt it, scope in hand I've seen that the DC component of your audio files is very critical it lengthens/shortens pulses ~ randomly (depends on the data being sent because the dc component of the "one" symbol is not zero) and that produces receive errors. So the 9600 waveforms almost never work (with reason), and the 8000 bps (symbols are symmetrical -> no DC component) only after a few tries tweaking the volume to get it exactly right, because it does not account for the delay of the opamp when/if it goes into saturation.
Egan Ford
2018-02-16 00:44:50 UTC
Permalink
Raw Message
Post by Jorge
Post by Egan Ford
Post by Jorge
Oh, sorry. I say so because it didn't work so well for me. You have to find the proper volume setting and that's very very tricky. As I told you before when it works it's great.
AFAIK, for everyone else max volume works.
Sorry, but I doubt it, scope in hand I've seen that the DC component of your audio files is very critical it lengthens/shortens pulses ~ randomly (depends on the data being sent because the dc component of the "one" symbol is not zero) and that produces receive errors. So the 9600 waveforms almost never work (with reason), and the 8000 bps (symbols are symmetrical -> no DC component) only after a few tries tweaking the volume to get it exactly right, because it does not account for the delay of the opamp when/if it goes into saturation.
You're doubting the 100s (perhaps 1000s) of people that haven't had any
problems.
Anthony Ortiz
2018-02-16 00:51:15 UTC
Permalink
Raw Message
Post by Egan Ford
Post by Jorge
Post by Egan Ford
Post by Jorge
Oh, sorry. I say so because it didn't work so well for me. You have to find the proper volume setting and that's very very tricky. As I told you before when it works it's great.
AFAIK, for everyone else max volume works.
Sorry, but I doubt it, scope in hand I've seen that the DC component of your audio files is very critical it lengthens/shortens pulses ~ randomly (depends on the data being sent because the dc component of the "one" symbol is not zero) and that produces receive errors. So the 9600 waveforms almost never work (with reason), and the 8000 bps (symbols are symmetrical -> no DC component) only after a few tries tweaking the volume to get it exactly right, because it does not account for the delay of the opamp when/if it goes into saturation.
You're doubting the 100s (perhaps 1000s) of people that haven't had any
problems.
Millions!

Jorge
2018-02-12 19:36:32 UTC
Permalink
Raw Message
Well I mean about 14 kbps max wire speed, if on top of that you add compression then a zipchip may be a good thing to avoid additional inter frame delays while decompressing the packets.
Loading...