CrazyF ZX Spectrum demo Airwolf music + digital samples

I wonder how it was done that while playing the digi speech sample
the scroll still goes smoothly.

It was run on ZX 128 emulator without any addidional hardware.
Usually scrolls are run in the interrupt mode 2,
in 50Hz, the music is also played on interrupts

While playing samples interrupts are disabled by programmers,
The music stops, so it's ok - this seems that the interrupts are disabled.
So why the Hell the scroll doesn't stop or move slower?

In digital music trackers while playing even the cursor stops,
because playing digis takes all CPU time to preserve the best quality.
There are some exceptions for example in the game Firefly,
that a digi music is played and on a piano keyboard on the screen
the played notes are highlighted, but these are single machine code instructions
and no human can hear, because it takes microseconds,
Other effect you can hear in games Agent X2 and Chronos, where
the music is played by the beeper and the preset drum effect is released on AY chip,
but it is just one OUT instruction sent to the soundchip.

More complicated routines were used in 4 channel (AY+ beeper) music in Chase HQ
or scrolling pixels in Dark Fusion while the beeper plays music,
It could be done (not easy, but possible), yet scrolling text takes much more time.

If my question is stupid, forgive me, I stopped working on ZX in 1991.

Category:

Science & Technology

Tags:

• ZX
• spectrum
• digital
• sample
• music
• russian
• demo
• airwolf
• ay
• chip
• tune
• scroll
• scroller
• interrupts

[Abrimaal]

@wlcina I know, but playing samples (like voice synthesis) takes a lot of CPU power and I wonder why the scroll still runs smoothly on 50Hz interrupts.

[wlcina]

The woice is made with noise channel on AY chip