STACK Opeode it Pus Pus Pus Pus PUSH Operand srs tit gees gees 1 Lag Suck Pointer 1 La tho stack poimsr register with» 162i aiess The EX! insractions were dicased in Chapter 7 Store Regier Param Sack 1D This is. byt nsstion 1 Ieoopies the conten ofthe speed ester pron the stack as described below 10 The tack pln eps s decremented, and the con- tens of te high-order epter (eg. reisor B) se ‘apie in he cation sh by the stack pointer ester (© Te stack pointer eps agin decremented, a the content ofthe laure oie (erie C) ae copied in tht action 10 The operands, D, and H represent register pais BC, DDE, ond IL, respeatively 11 The opera PSW resents Progra Status Wont meaning the contents ofthe secular al he Has Retrieve Reps Pi rom Sick 10 Thiisa rhs insrction 1 teeopis the contents oF ths top eo memary cations ‘ofthe ck ino the specified regis pt 12 Fist the coments ofthe memory leatio inated by ‘he ack pine register se copied into he low-order gine (eg. register Land then the tick pointer re ister is incremented by 1 1D The comers ofthe next memory location are coped Into te high order epee. seis), and the stack pointer register i gai incremented by 1Cees Prey ns Contents onthe Stak and in the Rect Aor tho PUSH InstructionPROBLEM STATEMENT Write a program to perform the following functions: 1, Clear all the fags. 2. Load OOH in the accumulator, and demonstrate thatthe Zero fla data transfer instruction, 3. Logically OR the accumulator with itself to set the Zero flag, and display the flag at PORT! or store all the flags on the stack. not affected by theMachine ‘Code nstretions| XI SPXXOOIE MMVI L008 ust Por PSW ME ACOEL ust PSw por MOV AL. OUT PORTO MVIA.oOH ORAA PUSH FSW POP H MOV AL ANT AOH our port! her Comments Inialire the stack ‘Clear, Place (L) om stack “Clear Bags {Loa OOH ‘Save ays on sack ‘Retrieve flags in Display Mags ‘Load 00H again 'Set flags and vest CY, AC ‘Save flags on stack Retrieve flags in L ‘Mask all Mags except Z dof program Stig ia Mer Alera om oe irs we NVIADON oO gin * ” ona Sas an at C¥ md AC 5 Fusi'sw ‘Segsen * ir ae on Rag RegiserSUBROUTINE Opeode CALL RET Operand 16-bit memory address of a subroutine Call Subroutine Unconditionally (I This is a 3-byte instruction that transfers the program sequence (0 a subroutine address 7 Saves the contents of the program counter (the ad- dress of the next instruction) on the stack i Decrements the stack pointer register by two Jumps unconditionally to the memory location speci- fied by the second and third bytes. The second byte specifies a line number and the third byte specifies a page number This instruction is accompanied by a ret tion in the subroutine Return from Subroutine Unconditional This is a I-byte instruction C1 Inserts the two bytes from the top of the stack into the program counter and inerements the stack pointer register by two 1 Unconditionally returns from a subroutine instruMemory Address 2000 2040 2041 2042, 2043 205F 2070 207F 2080 2398 23FF 2400 LXI SP2400H Lu CALL. 2070H NEXT INSTRUCTION | HLT First Subroutine Instruction + RET L Other Subroutines Empty Space 4 sTnitialize the stack pointer at 2400H ;Call the subroutine located at 2070H. This is + a 3-byte instruction The address of the next instruction following the CALL instruction :End of the main program ‘Beginning of the subroutine End of the subroutine ‘The stack is initialized at 2400HMemory Address 2040 2001 2082 2083 Mnemonics CALL 2070H INSTRUCTION Call subroutine located at them Comments very location 2070H 2000 Subroutine 2042 ——————- 2070 2043 205F 201FPROBLEM Write a program to provide the given owoff time to thre trafic lights (Green, Yellow, and Red) and two pedestrian signs (WALK and DON'T WALK). The signal lights and signs are urned onoft by the data bits of an output port as shown below: Data Bits On Time 1, Green 15 seconds 2. Yellow 5 seconds 3. Red 20 seconds 4. WALK 15 seconds 5. DON'T WALK 25 seconds ‘The traffic and pedestrian flow are in the same direction; the pedestrian should cross the road when the Green Sequence DON'T Hex Im Seconds. WALK WALK Red Yellow Green Code o Dy BR oP bh Db Db Bm ay 4 15 10:00 - 4H ol 20 oo = MH mt 4 ed ' o 0 © 0 0 = 8HMemory Address Xx00 o1 a 03 04 05 06 07 08 09 0A, op. oc op 0 OF 10 u 12 3 Code 31 9 LXI SPXX99 XX 3E START: MVIAAIH a m court port# PORTH 06 MVIBOFH oF cD CALL. DELAY 50 XX 3B MVIAS4H a4 pa our PoRT# PORTH 06 MYI BOS 05 cD ‘CALL DELAY 50 Mnemonics Comments sInitialize stack pointer at location XX99H ‘High-order address (page) of user memory ‘Load accumulator with the bit pattern for + Green light and WALK sign “Turn on Geen lioht and WALK sion :Use B as a counter to count 1Sseconds. + Bis decremented in the subroutine :Call delay subroutine located at XXSOH ‘igh-order address (page) of user memory :Load accumulator with the bit pattern for i Yellow light and DON'T WALK Turn on Yellow light and DON'T WALK 5 and turn off Green light and WALK {Set up 5-second delay counter14 15 16 7 18 19 1A 1B Ic 1D IE IF 20 Xxx 3E 90 D3 PORTH 06 4 cD 50 XX G 03 XX MVIA,90H OUT PORT# MVIB,14H CALL DELAY JMP START ;sHigh-order address of user memory :Load accumulator with the bit pattern for 3 Red light and DON’T WALK Turn on Red light, keep DON’T WALK on, and turn off Yellow light {Set up the counter for 20-second delay :Go back to location START to repeat the sequencesDELAY: This is @ [-second delay subroutine that provides delay according (othe parameter specified in register B XxX50 3 52 53 55 56 37 58 59 5A SB 5c sD SE sr 60 61 slnput: Number of seconds is :Ouaput: None Registers Modified: Register B bs DELAY: PUSH D FS PUSH PSW 1 SECOND: LXID,COUNT Lo HI 1B Loop: DCX D A MOV A.D BB. ORAE a INZ LOOP 55 XxX 05 DCRB Q JNZ SECOND 52 XX FI POP PSW DI POP D o RET specified in register B ‘Save contents of DE and accumulator Load register pair DE with a count for + I-second delay {Decrement register pair DE OR (D) and (E) to set Zero fla Jump to Loop if delay count is not equal to 0 End of I second delay; decrement the counter Is this the end of time needed? If not, go back to repeat I-second delay High-order memory address of user memory Retrieve contents of saved registers sReturn to main program,