CAS files are a sort of container format for storing data as it was saved on cassette tapes. It was used primarily by BASIC, and there are several variants. The native BASIC used two formats for CSAVE (tokenized Basic program) and BSAVE (raw data image), the modulation used was PSK, same as ROM loader. BASIC-Korvet used a more sophisticated MSX CAS file structure, although probably only a subset of it. These files are FSK-modulated, which is not typical for Vector-06c.

I had 12K allocated for instruction ROM in my NEO430-based subsystem. And even with the incredibly compact msp430 code, the new features grew up in size and I have reached the 12K limit. It turned out however, that due to BRAM memory structure, allocating 16K (which is 8K 16-bit words) takes the same amount of BRAM blocks, so I was able to expand available ROM for even more features.

Supporting CAS files means generating a sound based on CAS file content on the fly. Loading happens as if it was a sound recording.

So far I have implemented loading BASIC 2.5 CAS files. BASIC-Korvet is a bit more involved, but it will be added soon.

Here's a little video update which I hope you'll find enjoyable.