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aneeshm
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Indore , Madhya Pradesh
Jul 2001
time: 10:55
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I can assume this idea is not original , it being so obvious . Yet I'm thinking of making it for my 12th grade project ( as a project common to physics ( the electronics parts ) and CS ( the programming parts ) ) . I'd say that the hardware is not too hard to rig together . The software could be pretty simple , too . But I don't know yet . Another thing is the maximum data density . I'd say that I can store data in octal or hex format to maximise data density .
To manage the input , I'm planning to use normal sound input and output ports . Then I can send the data to standard sound output so that I can use a cable to plug it into the mike port of a normal audio cassette recorder to make recording easier , and use the headphone/standard output port of a player and mike port of a computer to copy data from the tape back to the computer .
Can the resident experts here tell me if this is feasible ?
Last edited by aneeshm on 10-02-2005 at 21:36
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Dry
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Brussels
Sep 2000
time: 06:25
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quote:
Originally posted by aneeshm
I'm planning to use it ( actually , not use it , just make a project out of it which will look as it it has some purpose ) to archive/backup data . I'd like to know how much data a disk can store . |
Difficult to say... I don't remember.
The computer of that time had... say, 16K of RAM, so games had to be smaller than that.
iirc, we had ~20 games on a tape, so it makes something like, maximum 320K. But it is pure guess from my part. In fact, I have no idea...
You know, in between for backups, they invented ZIPs and JAZZs and DATs.
If I were you I'd try something more ... inovative, like a car pulled by horses, or an iron boat propulsed by a steam engine.
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Geronimo
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st cloud USA
Jan 1970
time: 05:25
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how about storing data on a VHS tape? Audio has been done but I don't recall that VHS ever was.
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reds4ever
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of the Spion Kop
Mar 2001
time: 05:25
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quote:
Originally posted by chegitz guevara
IIRC, you have to use high quality tape. Any old cassette won't do. |
Any old tape is OK, we used to copy games using Hi-Fi's with twin tape decks.
MikeH: IIRC the C64 tape deck used to operate at 600 baud and then veify the data, making it effectively 300 baud.
Last edited by reds4ever on 10-02-2005 at 22:39
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Zulu Elephant
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The greatest invention of all time was when you starting being able to play some simple game like space invaders WHILE the main game was loading...the minutes just flew by
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Cruddy
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quote:
Originally posted by aneeshm
I can assume this idea is not original , it being so obvious . Yet I'm thinking of making it for my 12th grade project ( as a project common to physics ( the electronics parts ) and CS ( the programming parts ) ) . I'd say that the hardware is not too hard to rig together . The software could be pretty simple , too . But I don't know yet . Another thing is the maximum data density . I'd say that I can store data in octal or hex format to maximise data density .
To manage the input , I'm planning to use normal sound input and output ports . Then I can send the data to standard sound output so that I can use a cable to plug it into the mike port of a normal audio cassette recorder to make recording easier , and use the headphone/standard output port of a player and mike port of a computer to copy data from the tape back to the computer .
Can the resident experts here tell me if this is feasible ? |
Yes it's feasible although I suspect you will need to learn some more about electronics before you can do it.
You'll have to decide which frequencies mean what in the backup, and design the circuits as much as the software to do it.
Back when hard drive sizes were 20Mb or so, companies sold kits to back up onto video tape - dedicated tape drives were very expensive and so home VCRs were used.
Haven't seen one of them for 12 years or so.
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DanS
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Kickball Capital of the World
Jan 1970
time: 00:25
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This shouldn't be extremely difficult and shouldn't require additional hardware. As you say, all you would need to do is use an audio card with output and input. Everything could be done in software. An audio card like this...
http://www.m-audio.com/products/en_...ion71-main.html
...would provide 96 Khz recording from line in, or a theoretical maximum of 96k baud. Of course, you would need to store the data in binary, with a checksum of some sort every x bits. Actual bit density would be much less, because of the limitations of the audio tape drive. You would just have to do a testing regime. The error rate/density might be a good color chart for your teachers to be impressed with.
As a general rule, you can store a lot on tape. You can store several tens of gigabytes of data on a tape through an ordinary digital camcorder, for instance.
Last edited by DanS on 11-02-2005 at 01:17
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Sir Ralph
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Long live teh Schwampel!
Dec 2001
time: 06:25
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Been there, done this.  In the eighties, in East Germany. It was frigging difficult to get the DM for a home computer (Commodore 64 or Atari 800). To get the additional money for a datassette was impossible, at least for me. Everyone OTOH had an ordinary cassette recorder, so why not use it for data storage?
The problem with the storage is, that you have to create vibrations (to make the sound for storage). Obviously, if stored directly, the bit sequence 000000... would produce silence on the tape. But if you have a sequence of 111111..., it would also translate into silence, because there are no oscillating bits. Our solution was to have every bit represented by a triple of bits:
0 = 010
1 = 011
So only every third bit counts.
Since every bit starts with 0 and has an upflank, it translates into a vibration, which can be stored at the tape (it sounds abominable). There is no silence possible. We had a block size of 256 bytes. Each block had a header of "5A5A". That was important, because you have to catch the phase, as on some systems you got the vibrations inverted. So if the header was "A5A5" (the inverse of "5A5A"), we just inverted every bit of the block. The blocks also had counters, so if a block was rejected due to a checksum error, it was enough to rewind a little bit, usually the system caught up.
We called it "turbo" and reached a speed of 4000 baud. We made experiments up to 6000, it worked, but not safely. 4000 baud worked wonderful. It had a little adapter, but I can't tell anything about it (hardware embryo here). I just wrote the driver. It was fun. Those were the days.
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Mercator
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Sorekara no Nanimo
Jan 1970
time: 06:25
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Why not use different sound frequencies? That is, you could either have 16 different frequencies for each nibble (i.e. 4 bits). The result would be single tones. Or you could make it a little more complicated and instead use 8 frequencies for each byte. The result will be "chords" which you could decompose with some spectrum analysis.
... But I'm guessing that's sort of what you had in mind already, aneeshm, since you mentioned octal/hex and recording with a simple mike (edit: oh wait, you weren't).
Last edited by Mercator on 11-02-2005 at 06:04
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10-02-2005 17:43
I suppose something like that. I had never heard of that before. I was thinking 8 different frequencies each representing one bit in a byte. So silence would be 0x00, all 8 tones would be 0xFF. Higher frequencies would help a bit, but I guess you're right...
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