[colorforth] Subject: Re: [colorforth] "Play and Display"

[Nick Maroudas <alice@xxxxxxxxxxxxxxxxxxxxxxx>]

Nick here:  

Tutorial:  Play and Display

The words "pause" and "blk" can be used to display a
music score while playing it, block by block. Blk holds
the block number, and Pause refreshes the display. 

For example, the word "Handel" is on block 68 of Howerd
Oakford's CFDOS4 (see my tutorial on Monday, 10 Mar
2008  Re: [colorforth] Hello - and where to begin?). 
One can redefine the word Handel so that it displays
block 68 before playing Handel's gavotte.  

: Handel  68 blk !  pause  Handel ; 

One can then define a word to display the next block as
well 

: pd ( Play & Display)  blk @  2 +  blk !  pause  ;  

This will cause  Handel  to chain block 70 after it has
played block 68

: Handel  68 blk !  pause  Handel  pd ;  

That way, one can chain a Play & Display music score,
block after block.  If you want to skip  n  blocks

: ppd ( n>>)  blk @  +  pause ;  

and redefine pp 

: pp  2 ppd ;  

I have used this method to Play & Display 114 bars of
Beethoven's string quartet Rasoumovsky 1, each bar
being sourced on a separate block. As far as I can
judge by ear, the multitasker word  "Pause"  does not
introduce a perceptible pause between the bars.  Thus,
CF's display refresh seems to have a low enough latency
for the purpose of bar by bar P&D. 


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