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- start-microcode regressfreq
- \ Reads 16-bit frequency from COMM, generates square
- \ wave at half frequency PIN2
- : 1+ d# 1 + ;
- : @ dup c@ swap 1+ c@ swab or ;
- : ! over swab over 1+ c! c! ;
- : main
- d# 0 P2_DIR c! \ Make P2 an output
- \ Drive P2 high when raster is past line COMM+0
- COMM+0 @ FREQHZ c!
- begin
- FREQTICK c@ P2_V c!
- again
- ;
- end-microcode
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