DC2N5-LC PRG file playback with Turbo Tape 250 encoding completed!

Today after work I managed to finish the DC2N5-LC code that, given a PRG on the SD Card as input, streams out a signal for the Commodore 64 tape port using the Turbo Tape 250 encoding.

Preliminary tests seem good so far. As usual, I am using DC2N4 to dump the signal coming out of DC2N5-LC in order to verify that things look as they should.

Here’s a screenshot that shows the quality of the signal:

Sampling DC2N5-LC's PRG playback as Turbo Tape 250 with DC2N4-LC

Sampling DC2N5-LC’s PRG playback as Turbo Tape 250 with DC2N4-LC

And here’s a couple of screenshots from TAPClean Front End too:

Inspection of the signal produced by the DC2N5-LC's PRG loader, dumped with DC2N4, in TAPClean Front End

Inspection of the signal produced by the DC2N5-LC’s PRG loader, dumped with DC2N4, in TAPClean Front End

Inspection of the data encoded by the DC2N5-LC's PRG loader, dumped with DC2N4, in TAPClean Front End

Inspection of the data encoded by the DC2N5-LC’s PRG loader, dumped with DC2N4, in TAPClean Front End

Finally, here’s a snippet from TAPClean’s report:

Header test : PASS [Sig: OK] [Ver: OK] [Siz: OK] 
Recognition test : FAIL [104276 of 104279 bytes accounted for] [99%] 
Checksum test : PASS [1 of 1 checksummed files OK] 
Read test : PASS [0 Errors] 
Optimization test : FAIL [0 of 2 files OK]

Not bad at all, isn’t it? 🙂

You can probably guess what I think I should do next: combine the CBM ROM and TT250 signal generators so that a tiny CBM ROM boot is generated first, executes and loads the TT250 part, just as I did for my PRG2TAP PC tool. In this way users would not have to load a TT250 utility beforehand.
The next stage could be to produce a signal using Action Replay’s Superturbo so that anybody with one of these cartridges could load a PRG file through the tape port on a Commodore 64 quickly. Maybe this is a bit too much, but never too much for true tape enthusiasts 🙂

This entry was posted in Retrocomputing, Technical and tagged , , , , , . Bookmark the permalink.

2 Responses to DC2N5-LC PRG file playback with Turbo Tape 250 encoding completed!

  1. PhilN2015 says:

    Hi, what do the green and blue vertical lines on the GUI represent?

    • luigidifraia says:

      The blue bands represent 3 frequency ranges centred around the 3 square wave frequencies used by the CBM ROM encoding. Green bands show the frequencies observed in the incoming signal and are plotted over time in order to appreciate how they change, e.g. when the encoding changes.

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