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Assembly codes question (keypad)

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daredave

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Good day sir! can anyone explain me how these codes work in a more detailed way? specially the "keytable"? and what does "dt" stands for? I really need to fully understand these set of codes.. thank you all!:D

Code: 
ram_start	EQU 0x0c
keycode		EQU ram_start+5
rowcnt		EQU ram_start+6
colcnt		EQU ram_start+7

Code: 
keytable	
		movf keycode, W
		addwf PCL, F
		dt 0x60
		dt "123a"
		dt "456b"
		dt "789c"
		dt "*0#d"

keyscan		
		clrf keycode
		movlw 4
		movwf rowcnt

		movlw 0xfe
		tris PORTA

rowscan	movlw 0xa0
		call udelay
		swapf PORTB, W
		movwf colstatus

		movlw 4
		movwf colcnt

colscan	incf keycode, F
		rrf colstatus, F
		btfss STATUS, C
		goto keytable 

		decfsz colcnt, F
		goto colscan

		bsf STATUS, C

		bsf STATUS, RP0
		rlf TRISA, F 
		bcf STATUS, RP0

		decfsz rowcnt, F
		goto rowscan
		retlw 0
 

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