Intel mcs-48 manual Jump to Timerroutine, IFTF=1, Jump to Location 53 DEC, Jump to Countroutine

INSTRUCTION SET

JTF address Jump If Timer Flag Is Set

I0 0 0 1 I0 1 1 0 I Ia7 a6 as a4 Ia3 a2 a1 ao I

This is a 2-cycle instruction. Control passes to the specified address if the timer flag is set to one, that is, the timer/counter register has overflowed. Testing the timer flag resets it to zero. (This overflow initiates an interrupt service sequence

if the timer-overflow interrupt is enabled.)

(PC - )-- addr	If TF=1
O 7
(PC) = (PC)+2	If TF=O
Example: JTF1: JTF TIMER	;JUMP TO 'TIMER'ROUTINE
	;IFTF=1

JTO address Jump If Test 0 Is High (Not in 8021)

I0 0 1 1 I0 1 1 0 I Ia7 a6 as a4 Ia3 a2 a1 ao I

This is a 2-cycle instruction. Control passes to the specified address if the test 0 signal is high (=1).

(PCO-7)-- addr	If TO=1
(PC) = (PC)+2	If TO=O
Example: JTOHI: JTO 53	;JUMP TO LOCATION 53 DEC
	;IF TO=1

JT1 address Jump If Test 1 Is High

I0 1 0 1 I0 1 1 0 I Ia7 a6 as a4 Ia3 a2 a1 ao I

This is a 2-cycle instruction. Control passes to the specified address if the test 1 signal is high (=1).

(PCO-7)-- addr	If T1=1
(PC) = (PC)+2	If T1=O
Example: JT1HI: JT1 COUNT	;JUMP TO 'COUNT'ROUTINE
	;IF T1=1

JZ address Jump If Accumulator Is Zero

This is a 2-cycle instruction. Control passes to the specified address if the accumulator contains all zeros at the time this instruction is executed.

(PCO-7) -- addr	If A=O
(PC) = (PC)+2	If At-O
Example: JACCO: JZ OA3H	;JUMP TO LOCATION 'A3'HEX
	;IF ACC VALUE IS ZERO

Mnemonics copyright Intel Corporation 1976.

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