When you fastforward, rewind, play or record your tapes with your Datassette on your Commodore 64, there's actually more going on than you might think. It's actually up to software, whether the KERNAL ROM code, or the game you're playing, or your own program you wrote, to allow the cassette deck to be powered and actually move the tape. We look at several examples, both commercial games, and our own userwritten BASIC programs to help demonstrate this, and even take a peek at the C64 system interrupt code.

Links to other videos mentioned:
"99.8% Compatible? The C64 Mode of the Commodore 128"    • 99.8% Compatible? The C64 Mode of the...  
Software on tape: "Software on Cassette Tape in USA and Canada Apple, TRS80, Atari, PET to Commodore 64"    • Software on Cassette Tape in USA and ...  

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Index:
0:00 Datasette compared to other cassette decks
6:11 C64 and Datasette: working together
8:58 Last V8: gameplay; no tape control
12:02 Cauldron II: gameplay; motor always running
15:01 Road Toad, Lazer Force: two other behaviours
18:25 ?PEEK(1) 4 states
21:04 The bits of location 1
26:57 Slowing down the system interrupt
30:10 REALLY slowing down the system IRQ
35:15 Diassembling the KERNAL IRQ code: tape routines
40:06 Using Tape Motor Interlock
44:15 Conclusion and thanks!