1. Compsci 210 Tutorial Four

2. agenda Last week homework Sequential circuit - difficult
Lc-3 simulator

3. Exercise 2.8
Determine the truth table for this decoder (Solution on Piazza)
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4. Two type of logic circuits
Combinational Circuit for computing
always gives the same output for a given set of inputs
Decoders – convert S into control signals
Multiplexers – select inputs and outputs
ALU (Arithmetic and Logic Unit) – operations on data
Sequential Circuit for storing
stores information
State machine – coordinate control signals and data movement
Registers and latches – storage elements
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5. Latches The SR Latch (NOR) Consider the following circuitQ R Q Q S S Q Q S Q
Symbol
Circuit
R S Q
Qprev (HOLD)
0 1 1
1 0 0
1 1 ?
Q represents current output
Qprev represents previous output. (at last time)
Not allowed
Function Table
Why we need “HOLD” state?
Although SR LAtch is one of the most important fundamental methods of didgital storage,it is not often used in practice (because of undefined state) - However forms the basis of the more complex latches that we will be dicussing

6. You ought to be able to figure this one out yourself!
Latches
The SR Latch(NAND)
NAND Form produces similar result from inverted inputs R
R S Q
0 0 ?
0 1 0
1 0 1
1 1 Qprev Q R R Q Q
Not allowed Q S S S Q Q
Hold
Function Table
Circuit
Symbol
You ought to be able to figure this one out yourself!

7. Master-Slave Flip flop
Reduce the current noise on the circuit D CK
Qcurrent
Qnext ↑ X 1
At the beginning of each clock cycle
Again: To reduce the noise possibility

8. Von Neumann Model

9. Instruction Processing

10. LC-3 an assembly language (low-level programming language)
a type of educational programming language
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11. Why assembly language Human logic: We are here Circuit:
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12. High level languages Assembly language Machine code
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13. LC-3 simulator & LC-3 editor
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14. LC-3 simulator & LC-3 editor
You can edit your program here using binary code, hexadecimal code and assembly code. 
After finish editing, you can export to .obj file which can be run by LC3 simulator.

15. LC-3 simulator & LC-3 editor
virtual computer which execute assembly code
Simulator
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16. LC-3 Notes The simulator and the editor are separate programs
The simulator is available for Windows (also Linux/Java/etc)
The lab computers should have LC-3 included
The LC-3 software can be executed from a flash drive
Download from :
Goolge: lc-3 simulator
canvas if needed
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17. The LC-3 Files
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18. The LC-3 Files
After installation, you will see 2 exe programs (windows): LC3Edit.exe and Simulate.exe.

19. LC-3 Editor
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20. LC-3 Editor The editor is used to enter your LC-3 instructions
You will save your programs into the .asm format
The editor will also assemble your .asm files into .obj files which can be run on the simulator

21. example.asm
.ORIG x3000 LD R2, ZERO LD R0, M0 LD R1, M1 LOOP BRz DONE ADD R2, R2, R0 ADD R1, R1, -1 BR LOOP DONE ST R2, RESULT HALT RESULT .FILL x0000 ZERO .FILL x0000 M0 .FILL x0004 M1 .FILL x0803 .END
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22. LC-3 Simulator

23. LC-3 Simulator
The simulator is used to execute your assembled LC-3 machine code
You will load the .obj files you create into the editor
The editor gives you a very detailed view of what is happening as your machine code is executed

24. Lc-3 simulator
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25. Example: LC-3 ADD Instruction
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26. Demonstration Complete the following tasks in LC-3.
Write a program in the LC-3 Editor.
Assemble a program in the LC-3 Editor.
Load and execute a program in the LC-3 Simulator.
Set breakpoints in the simulator to pause execution.
Step forward through your executing program one line at a time.
Modify a register value during program execution.