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Commodore Datasette mod

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rorypoole

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I have some non working Commodore datasettes and I plan to fix them and upgrade them to store data at much higher data rates.
first I will have a C2N232 a datasette to rs232 adapters that's good up to 38400 bps full-duplex circuit and a small 14.4k modem to use to encode the data onto the tape, it looks like there will be enough audio bandwidth for 2 modem channels per side on the audio tape in the mono datasette so I will have switches for normal to high data rate, and channel 1 to 2, I will have to work out a good system to keep the speed consent, maybe I will have to fit a stepper motor?

http://www.zimmers.net/anonftp/pub/cbm/crossplatform/transfer/C2N232/C2N232.html

what do you think about modding non working Commodore hardware?

this will be to use with a damaged commodore 4016 and working commodore 8032
 
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C2N232 is cool, I've got one of those myself. However I don't understand the addition of a modem, just the serial connection itself should be good enough. Also the full size of a C2N is far from required for a such interface.

Generally, I'm all for modding stuff that doesn't work or which there is a great abundance of. For example, C2N's grow on trees and everytime I pick up any Commodore computer, I'm destined to get another C2N in the deal. Last time I counted, I think I came to five or six spares apart from the one I'd use if I ever plugged in a tape anymore.
 
the commodore datasette is very slow and stores only a small amount of data, but I would still like to use tapes to store data with my commodore, and I was planing to use the C2N232 circuit in the datasette and the modem to encode the digital information onto the audio tapes
 
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carlsson said:
Ah, so approximately 3000 bps turbotape is too slow, so you're trying to implement 14400 bps modemtape.
Click to expand...

I will have to look into turbotape but using a modem could boost the data rate 5x turbotape or 50x normal and store upto a possible 4.68mb per 30m tape per channel

(Datasettes could typically store about 100 kByte per 30 minute side. The use of turbo tape and other fast loaders increased this number to roughly 1000 kByte.)
from http://en.wikipedia.org/wiki/Commodore_Datasette

http://en.wikipedia.org/wiki/Modem under (List of dialup speeds)

its a project I have been thinking about years before I got the two commodors I am currently working on, but could be useful to use with the petpix http://www.bitfixer.com/bf/petpix or use the code from Orb - "No Pets Allowed" - Commodore PET demo to play films on the commodores http://www.youtube.com/watch?v=ktUguF1TnJk
 
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but if I use both the commodores datasette ports and two modems and both channels I could store upto 9.3mb per 30m audio tape or upto 100x normal! but I will have trouble finding two 14.4 or faster modems that will fit in the old Commodore Datasette case.
I will have to open up my Datasettes and see how much space I have to use.
the modems will probably need to be external
 
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can two datasette ports be used at the same time? and with two C2N232 type adapters at enhanced data rates?
 
The PET series support two Datasettes, but the VIC/C64 only can handle one at a time. There were various hacks to connect two recorders though, to take backups of tapes. Beware about the power consumption, as the cassette port is only dimensioned for so many mA. Of course you probably will power your 14.4K modems externally, so there won't be any power draw from the computer.
 
rorypoole said:
can two datasette ports be used at the same time? and with two C2N232 type adapters at enhanced data rates?
Click to expand...


On various PET versions, the write (record) signal line is shared between the two cassette ports, so you can write the SAME data on two cassettes at the same time, but not different data. The read (playback) signals of the cassette ports are separate so in theory it's possible to read data from two cassettes at once, but because they are mechanically separated, you can't count on data coming in at the same speed (let alone completely synchronous). Also, the on-board software was never designed to read from two cassette ports at once, so I expect that this would require some complicated Assembly software and I read (in the "Commodore: a company on the edge" book) that Chuck Peddle had a lot of trouble getting the cassette routines just right...

Good luck!

===Jac
 
jac_goudsmit said:
On various PET versions, the write (record) signal line is shared between the two cassette ports, so you can write the SAME data on two cassettes at the same time, but not different data. The read (playback) signals of the cassette ports are separate so in theory it's possible to read data from two cassettes at once, but because they are mechanically separated, you can't count on data coming in at the same speed (let alone completely synchronous). Also, the on-board software was never designed to read from two cassette ports at once, so I expect that this would require some complicated Assembly software and I read (in the "Commodore: a company on the edge" book) that Chuck Peddle had a lot of trouble getting the cassette routines just right...

Good luck!

===Jac
Click to expand...
I can have synchronous playback of data as both data streams will be on the same tape but one will be frequency shifted up as an audio cassette has more bandwidth than a modem needs at least two times.
thanks for the info
 
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