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I have recently heard about recording video games' binary codes from radio programmes which was quite popular several decades ago.

The computer name was ZX Spectrum. The general idea behind the process was that you had to turn on recording when the radio program started. The whole radio program sounded like a high-pithced noise to human ear but overall it could be decoded to a binary file and run by ZX Spectrum.

I would like to learn about the technology which made this cool process work. As @hotpaw2 mentioned in the comment, it might be quite interesting to learn something about the modulation scheme and protocols used to transfer the programs over RF.

Lately, I learnt some basics about the signal modulation schemes, so I think I am capable of understanding general ideads behind this technology.

What are these modulation schemes and protocoles used in this particular technology? Why it usually took over 15-20 minutes to transmit the whole program over RF.

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  • $\begingroup$ Hi Mateusz Piotrowski. This question does not appear to me to be about radio; it is more of a computer history or vintage gaming question, as the use of radio in the situation you describe is really just incidental. Additionally, Stack Exchange in general works very poorly for questions explicitly seeking off-site resources. If you're willing to edit your question into one that asks a specific question (inviting answers which might be supported by additional references, rather than asking for the references themselves) this might be eligible for migration to a more suitable site. $\endgroup$
    – user
    Apr 29 '15 at 9:32
  • $\begingroup$ Thank you Michael! I've found out that this computer was called ZX Spectrum. I am sorry that this question might seem off-topic but I thought it is somehow releted to the history of radio. Nevertheless, I am not able to ask a more specific question yet. When I learn some more about the whole process I might ask a radio-oriented question. $\endgroup$
    – Mateusz Piotrowski
    Apr 29 '15 at 9:52
  • $\begingroup$ It isn't really more related to radio than asking about a particular song by a particular famous musician would be. Radio in your case provided the transmission mechanism; another transmission mechanism that could easily be provided would be simply an AF cable, or a recording to an audio CD, or anything else to get the audio from point A to point B. Hence, the question is not about the technology of radio, but rather about something that was done using radio as one part of the overall system. That makes it off topic for the Amateur Radio Stack Exchange. $\endgroup$
    – user
    Apr 29 '15 at 11:08
  • $\begingroup$ For more about what we consider on-topic and off-topic here on the Amateur Radio Stack Exchange, see What topics can I ask about here? in the site's help center. Again, note that the question can probably be turned into something that is on-topic on another site; for a vintage gaming question, I would consider Super User or Arqade. $\endgroup$
    – user
    Apr 29 '15 at 11:09
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    $\begingroup$ It most likely used 300 baud "Kansas City Standard" modulation, or a variant - check Wikipedia for details. Programs were also transmitted in BASICODE, a cross platform BASIC dialect, and transmitted at 1200 baud FSK. $\endgroup$
    – scruss
    May 6 '15 at 0:41

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