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Simplicalc tape on NTSC VIC-20 vs. VIC-20 PAL


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I have the chance to get Simplicalc on cassette, # VIC 3302. It requires the 16K RAM extension, which I now have.


The potential issue is.... this particular version is UK based, and I am not sure if would run on a USA NTSC Vic-20 or if it would have load and run issues on the DATAMASTER, as I have learned in my travels that there are slight timing differences with the NTSC and the PAL versions.


Anyone have any information here or experience if that above # tape would work on an NTSC VIC-20?


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There is a slight difference in clock frequency. I believe both the C64 and VIC-20 run at exactly 1.00 MHz in NTSC, but in PAL the C64 is closer to 0.98 MHz and the VIC-20 is 1.01 or even 1.02 MHz. When it comes to timing pulses on a cassette, every hertz makes a difference. Sometimes it can work, often it fails. This is why programs to generate TAP and WAV from other files need to know the target machine.

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  • 3 weeks later...

Look like you can download the software from this link:




I would suggest loading up VICE and testing them in NTSC mode.  From the look of it - a simple enough text-only display - you should have no issues.


VIC20 tapes sold in the PAL market will load fine on an NTSC machine, its just a question of if the software itself has any timing dependent issues.  The greater concern in my mind is if a 40 year old tape would load at all.


Good luck!


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