decus
NO. 8-292  FFT - #4 Symbolic
    q      3/7/69   600-777

	6424 / INITIALIZE CLOCK
	CLA CLL
	ADCC	/	CLEAR A/D CHANNEL
DCA INDX / INITIALIZE INDEX
	CMA
	DCA CNTR / SET ODD/EVEN COUNTER
	TAD NUM
	CIA
	DCA PNTR / SET POINTS COUNTER
SAMWT,	ION / INTERRUPT WAIT ROUTINE
HERE,	JMP HERE
SER0,	6424 / RESET CLOCK
	CLA CLL
	ADCV / SAMPLE SIGNAL
	TAD INDX
	6777 / BIT INVERT INDEX
	MQL
	CLA MQA
	TAD RSA / SET DATA ARRAY ADDRESSES
	DCA RA
	CLA MQA
	TAD ISA
	DCA IA
ORDF,	ADSF
	JMP .-1
	ADRB	/ READ A/D
	TAD HALF
	CLL RAL / SCALING TO PREVENT
	ISZ CNTR / OVERFLOW
	JMP .+6
	DCA I RA / EVEN POINTS TO REAL
	CLA IAC / ARRAY
	ADSC / SET A/D TO CHANNEL 1
	CLA CLL
	JMP .+7
	DCA I IA / ODD POINTS TO IMAG ARRAY
	ADCC / SET A/D TO CHANNEL 0
	CMA
	DCA CNTR
	ISZ INDX / INCREMENT INDEX
	ISZ PNTR
	JMP SAMWT
	JMP I FFTI / SAMPLING COMPLETE
OUTPT,	6077 / SET CRT INTENSITY
	DCA ARG1
	TAD NUM
	CIA
	DCA CNTR
	LAS
	CLL RAL
	SZL CLA / IF BIT 0=0, DISPLAY REAL
	JMP .+4 / ARRAY; IF 1, DISPLAY
	TAD RSA / IMAG ARRAY
	DCA RA
	JMP .+3
	TAD ISA
	DCA RA
DISPL,	TAD ARG1 / DISPLAY RESULTS
	DXL
	IAC
	DCA ARG1
	TAD I RA
	CLL RAR
	CLL RAR / SHIFT FOR DISPLAY
	DYS
	CLA
	ISZ RA
	ISZ CNTR
	JMP DISPL
	JMP OUTPT / DISPLAY SWEEP FINI
FFTI,FFT / POINTER TO FFT
HALF,1000 / OVER-RANGE PREVENTIVE
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