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Overview Review Trap Instruction Program in LC-3 machine language Use LC-3 Simulator
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TRAP Calls a service routine, identified by 8-bit “trap vector.” When routine is done, PC is set to the instruction following TRAP. vectorroutine x23input a character from the keyboard x21output a character to the monitor x25halt the program
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LC-3 Editor / Simulator Go to Authors Web page (http://www.mhhe.com/patt2 )http://www.mhhe.com/patt2 Download LC-3 (LC301.exe) LC-3 Edit LC-3 Simulate Review “Guide to Using the Windows Version of the LC-3 Simulator and LC-3 Edit”
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Example AddressInstructionComments x30F61 1 1 0 0 0 1 1 1 1 1 1 1 1 0 1 R1 PC – 3 = x30F4 x30F70 0 0 1 0 1 0 0 0 1 1 0 1 1 1 0 R2 R1 + 14 = x3102 x30F80 0 1 1 0 1 0 1 1 1 1 1 1 0 1 1 M[PC - 5] R2 M[x30F4] x3102 x30F90 1 0 1 0 1 0 0 1 0 1 0 0 0 0 0 R2 0 x30FA0 0 0 1 0 1 0 0 1 0 1 0 0 1 0 1 R2 R2 + 5 = 5 x30FB0 1 1 1 0 1 0 0 0 1 0 0 1 1 1 0 M[R1+14] R2 M[x3102] 5 x30FC1 0 1 0 0 1 1 1 1 1 1 1 0 1 1 1 R3 M[M[x30F4]] R3 M[x3102] R3 5 Opcode
![Example AddressInstructionComments x30F R1 PC – 3 = x30F4 x30F R2 R = x3102 x30F M[PC - 5] R2 M[x30F4] x3102 x30F R2 0 x30FA R2 R2 + 5 = 5 x30FB M[R1+14] R2 M[x3102] 5 x30FC R3 M[M[x30F4]] R3 M[x3102] R3 5 Opcode](http://images.slideplayer.com/16/5024596/slides/slide_4.jpg "Example AddressInstructionComments x30F R1 PC – 3 = x30F4 x30F R2 R = x3102 x30F M[PC - 5] R2 M[x30F4] x3102 x30F R2 0 x30FA R2 R2 + 5 = 5 x30FB M[R1+14] R2 M[x3102] 5 x30FC R3 M[M[x30F4]] R3 M[x3102] R3 5 Opcode")
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Example 1: Multiply This program multiplies two unsigned integers in R4 and R5. clear R2 add R4 to R2 decrement R5 R5 = 0? HALT No Yes Write program
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x3200 Clear Accumulator (R2)R2 <- 0 x3201 Add [R4] to AccumulatorR2 <- R2 + R4 x3202 Dec R5R5 <- R5 – 1 x3203 Do again if [R5] > 0BR p x3201 x3204 StopHALT Program to multiply [R4] x [R5] and place result in R2
![x3200 Clear Accumulator (R2)R2 <- 0 x3201 Add [R4] to AccumulatorR2 <- R2 + R4 x3202 Dec R5R5 <- R5 – 1 x3203 Do again if [R5] > 0BR p x3201 x3204 StopHALT Program to multiply [R4] x [R5] and place result in R2](http://images.slideplayer.com/16/5024596/slides/slide_6.jpg "x3200 Clear Accumulator (R2)R2 <- 0 x3201 Add [R4] to AccumulatorR2 <- R2 + R4 x3202 Dec R5R5 <- R5 – 1 x3203 Do again if [R5] > 0BR p x3201 x3204 StopHALT Program to multiply [R4] x [R5] and place result in R2")
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Write program Program to multiply [R4] x [R5] and place result in R2
![Write program Program to multiply [R4] x [R5] and place result in R2](http://images.slideplayer.com/16/5024596/slides/slide_7.jpg "Write program Program to multiply [R4] x [R5] and place result in R2")
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x3200 Clear Accumulator (R2)R2 <- 00101 010 010 1 00000 54A0 x3201 Add [R4] to AccumulatorR2 <- R2 + R4 0001 010 010 0 00 100 1484 x3202 Dec R5R5 <- R5 – 10001 101 101 1 11111 1B7F x3203 Do again if [R5] > 0BR p x32010000 011 111111101 07FD x3204 StopHALT1111 0000 00100101 F025 Program to multiply [R4] x [R5] and place result in R2 Test on Simulator
![x3200 Clear Accumulator (R2)R2 < A0 x3201 Add [R4] to AccumulatorR2 <- R2 + R x3202 Dec R5R5 <- R5 – B7F x3203 Do again if [R5] > 0BR p x FD x3204 StopHALT F025 Program to multiply [R4] x [R5] and place result in R2 Test on Simulator](http://images.slideplayer.com/16/5024596/slides/slide_8.jpg "x3200 Clear Accumulator (R2)R2 < A0 x3201 Add [R4] to AccumulatorR2 <- R2 + R x3202 Dec R5R5 <- R5 – B7F x3203 Do again if [R5] > 0BR p x FD x3204 StopHALT F025 Program to multiply [R4] x [R5] and place result in R2 Test on Simulator")
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Example 2 Compute sum of 12 integers. Numbers start at location x3100. Program starts at location x3000. R1 x3100 R3 0 (Sum) R2 12(count) R2=0? R4 M[R1] R3 R3+R4 R1 R1+1 R2 R2-1 NO YES Write program
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Example 2 – Sum integers form x3100 – x310B AddressInstructionComments x30001 1 1 0 0 0 1 1 0 0 0 0 0 0 0 0 R1 x3100 x30010 1 0 1 0 1 1 0 1 1 1 0 0 0 0 0 R3 0 x30020 1 0 1 0 1 0 0 1 0 1 0 0 0 0 0 R2 0 x30030 0 0 1 0 1 0 0 1 1 1 0 1 1 0 0 R2 12 x30040 0 0 0 0 1 0 0 0 0 0 0 1 0 0 1If Z, goto x3009 x30050 1 1 0 1 0 0 0 0 1 0 0 0 0 0 0Load next value to R4 x30060 0 0 1 0 1 1 0 1 1 0 0 0 0 0 1Add to R3 x30070 0 0 1 0 0 1 0 0 1 1 0 0 0 0 1Increment R1 (pointer) X30080 0 0 1 0 1 0 0 1 0 1 1 1 1 1 1Decrement R2 (counter) x30090 0 0 0 1 1 1 0 0 0 0 0 0 1 0 0Goto x3004
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Write a program to place the absolute value of the [R2] in R2 Sample program 4
![Write a program to place the absolute value of the [R2] in R2 Sample program 4](http://images.slideplayer.com/16/5024596/slides/slide_11.jpg "Write a program to place the absolute value of the [R2] in R2 Sample program 4")
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Example 3 - # Occurrences of Inputted Char
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Example 3 - # Occurrences of Inputted Char Program (1 of 2) AddressInstructionComments x30000 1 0 1 0 1 0 0 1 0 1 0 0 0 0 0 R2 0 (counter) x30010 0 1 0 0 1 1 0 0 0 0 1 0 0 1 0 R3 M[x3102] (ptr) x30021 1 1 1 0 0 0 0 0 0 1 0 0 0 1 1Input to R0 (TRAP x23) x30030 1 1 0 0 0 1 0 1 1 0 0 0 0 0 0 R1 M[R3] x30040 0 0 1 1 0 0 0 0 1 1 1 1 1 0 0 R4 R1 – 4 (EOT) x30050 0 0 0 0 1 0 0 0 0 0 0 1 1 1 0If Z, goto x300E x30061 0 0 1 0 0 1 0 0 1 1 1 1 1 1 1 R1 NOT R1 x30070 0 0 1 0 0 1 0 0 1 1 0 0 0 0 1 R1 R1 + 1 X30080 0 0 1 0 0 1 0 0 1 0 0 0 0 0 0 R1 R1 + R0 x30090 0 0 0 1 0 1 0 0 0 0 0 1 0 1 1If N or P, goto x300B
![Example 3 - # Occurrences of Inputted Char Program (1 of 2) AddressInstructionComments x R2 0 (counter) x R3 M[x3102] (ptr) x Input to R0 (TRAP x23) x R1 M[R3] x R4 R1 – 4 (EOT) x If Z, goto x300E x R1 NOT R1 x R1 R1 + 1 X R1 R1 + R0 x If N or P, goto x300B](http://images.slideplayer.com/16/5024596/slides/slide_13.jpg "Example 3 - # Occurrences of Inputted Char Program (1 of 2) AddressInstructionComments x R2 0 (counter) x R3 M[x3102] (ptr) x Input to R0 (TRAP x23) x R1 M[R3] x R4 R1 – 4 (EOT) x If Z, goto x300E x R1 NOT R1 x R1 R1 + 1 X R1 R1 + R0 x If N or P, goto x300B")
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Example 3 - # Occurrences of Inputted Char Program (2 of 2) AddressInstructionComments x300A0 0 0 1 0 1 0 0 1 0 1 0 0 0 0 1 R2 R2 + 1 x300B0 0 0 1 0 1 1 0 1 1 1 0 0 0 0 1 R3 R3 + 1 x300C0 1 1 0 0 0 1 0 1 1 0 0 0 0 0 0 R1 M[R3] x300D0 0 0 0 1 1 1 0 0 0 0 0 0 1 0 0Goto x3004 x300E0 0 1 0 0 0 0 0 0 0 0 1 0 0 1 1 R0 M[x3013] x300F0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 0 R0 R0 + R2 x30101 1 1 1 0 0 0 0 0 0 1 0 0 0 0 1Print R0 (TRAP x21) x30111 1 1 1 0 0 0 0 0 0 1 0 0 1 0 1HALT (TRAP x25) X3012Starting Address of File x30130 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0ASCII x30 (‘0’)
![Example 3 - # Occurrences of Inputted Char Program (2 of 2) AddressInstructionComments x300A R2 R2 + 1 x300B R3 R3 + 1 x300C R1 M[R3] x300D Goto x3004 x300E R0 M[x3013] x300F R0 R0 + R2 x Print R0 (TRAP x21) x HALT (TRAP x25) X3012Starting Address of File x ASCII x30 (‘0’)](http://images.slideplayer.com/16/5024596/slides/slide_14.jpg "Example 3 - # Occurrences of Inputted Char Program (2 of 2) AddressInstructionComments x300A R2 R2 + 1 x300B R3 R3 + 1 x300C R1 M[R3] x300D Goto x3004 x300E R0 M[x3013] x300F R0 R0 + R2 x Print R0 (TRAP x21) x HALT (TRAP x25) X3012Starting Address of File x ASCII x30 (‘0’)")
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Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Write program
![Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Write program](http://images.slideplayer.com/16/5024596/slides/slide_15.jpg "Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Write program")
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Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Find absolute value ADD R2, R2, #0 ; set cc14A0 BRzp +20602 NOT R2, R294BF ADD R2, R2, #114A1 R5 will contain x30 (#48), the offset for ASCII numbers AND R5, R5, #05B60 ADD R5, R5, #151B6F ADD R5, R5, #31B63 Check for [R2] >9 AND R4, R4, #0 ; init high digit holder to zero5920 ADD R2, R2, #-1014B6 BRn +20802 ADD R4, R4, #11921 BR -40FFC ADD R3, R2, #10 ; save low digit16AA If high digit = 0, don't display it ADD R4, R4, #0 ; set CC1920 BRz +20402 Display high digit ADD R0, R4, R51105 TRAP x21F021 Display low digit Add R0, R3, R510C5 TRAP x21F021 Halt TRAP x25F025
![Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Find absolute value ADD R2, R2, #0 ; set cc14A0 BRzp NOT R2, R294BF ADD R2, R2, #114A1 R5 will contain x30 (#48), the offset for ASCII numbers AND R5, R5, #05B60 ADD R5, R5, #151B6F ADD R5, R5, #31B63 Check for [R2] >9 AND R4, R4, #0 ; init high digit holder to zero5920 ADD R2, R2, #-1014B6 BRn ADD R4, R4, #11921 BR -40FFC ADD R3, R2, #10 ; save low digit16AA If high digit = 0, don t display it ADD R4, R4, #0 ; set CC1920 BRz Display high digit ADD R0, R4, R51105 TRAP x21F021 Display low digit Add R0, R3, R510C5 TRAP x21F021 Halt TRAP x25F025](http://images.slideplayer.com/16/5024596/slides/slide_16.jpg "Program to display absolute value of number in R2 (-99 >= [R2] >= 99) Find absolute value ADD R2, R2, #0 ; set cc14A0 BRzp NOT R2, R294BF ADD R2, R2, #114A1 R5 will contain x30 (#48), the offset for ASCII numbers AND R5, R5, #05B60 ADD R5, R5, #151B6F ADD R5, R5, #31B63 Check for [R2] >9 AND R4, R4, #0 ; init high digit holder to zero5920 ADD R2, R2, #-1014B6 BRn ADD R4, R4, #11921 BR -40FFC ADD R3, R2, #10 ; save low digit16AA If high digit = 0, don t display it ADD R4, R4, #0 ; set CC1920 BRz Display high digit ADD R0, R4, R51105 TRAP x21F021 Display low digit Add R0, R3, R510C5 TRAP x21F021 Halt TRAP x25F025")
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