COP3502: Introduction to Computer Science Yashas Shankar Program Translation

Second part of this course  We will spend 4 classes on Program Translation (chapter 6 from your AE textbook) and 3 classes on Hardware (chapter 7 from your AE textbook)  You need to have the textbook  You won’t have to do programming on program.cs.fsu.edu (but you still have to write some assembly programs on papers)  We will spend 4 classes on Ethics  Textbook is optional, but you may need it to do extra credits  We will also spend some times reviewing programming during this period

Extra credit  There will be 4 extra credits  2 for homework  2 for quizzes  For each extra credit, write a 5-page summary of one chapter from your “ethics” textbook

Alternative extra credit for homework  Do the homework that you want to have your score increase  Put your homework on your webpage  Write a 2-page summary of one chapter in Ethics textbook and put it on your webpage  15 points will come from your homework and 10 points from the summary. Grading policy on homework part will be tougher. Your homework has to be 100% correct or you will get at least 5 points off.

Alternative extra credit for quiz  Design a 10-question quiz related to the subject in the quiz that you want to increase your score. Put a “correct” answer for each question.  Put your quiz & solution on your webpage  Your base score will be 8 points. If your quiz is good, you will get 9 or 10. If it is bad you will get 0-7 points

Extra credit submission  You have to state what each extra credit is for, e.g. for quiz#4, asg#12, etc.  Normal 5-page summary extra credits  Print out and hand them to me  Alternative extra credits  Put on your webpage (and notify me)  You can start submitting your extra credit when we start “ethics for computer science” part  You have to submit your extra credit before the final exam

Program translation  Today lecture  Binary representation & machine language

Binary representation & machine language  Human language  “hello my name is pitch”  Machine language  “ ………………0101”  Machine language has only 0 and 1

How machine language work? Human: add one and two Machine: Code for ADD

Binary representation  Machine only understand 0 and 1  We need to convert numbers that we understand to what machines understand (and vise versa)

How to adds two numbers in binary representation? What can you notice here?

Binary representation – power of two bits

Binary representation – power of two bits = = = 192

How to convert binary number to decimal number? = 179 = =179

How to convert decimal number to binary number? 198 = ? 198 = = = =

Hexadecimal representation DecimalBinaryHex DecimalBinaryHex A B C D E F

How to convert binary to hexadecimal (and vise versa)? = 12FC = = 2F = = 23C = = 277 2F = CA3 =

Hexadecimal representation  Computer doesn’t understand it  Save people a lot of writing  Easier for people to understand  0, 1, 2, …………, 9, A, B, C, D, E, F

Coverting Hex to Decimal and vise versta  Hex to Dec: Hex  Binary  Decimal  Dec to Hex: Dec  Binary  Hex

Negative numbers in binary representation 8-bit positive numbers = {0,1,…… 255} = {0,1,…., (2 8 – 1)} 32-bit positive numbers = {0,1,……..,(2 32 – 1)} 8-bit numbers = {-128, - 127, ….. 0, 1, ….127} 32-bit numbers = {-2 31, ……. 0, 1, …… ( )}

Negative numbers in binary representation 8-bit representation: always have 8 bits Positive number: start with 0 (left-most bit) Negative number: start with 1 (left-most bit) Example:

How to represent negative number?  Use 2-complement system  Start from positive number  Reverse all ones and zeros (the output is said to be in one- complement form)  Add one to the output to get 2-complement representation Example: what is -5? 5 = Reverse = Add 1 = = 2-complement form of =

How to subtract number?  Subtract = add negative number  Example: 19 – 5  Start from 5 and change to -5 by 2-complement method  Add 19 and -5 together  More detailed example: solve19 – 5 in binary representation  Add 19 and (-5) together  Step 1: change 19 to binary representation  Step 2: change -5 to 2-complement form  Step 3: add them together  Step 4: change the number back to decimal

Computation within CPU  This course  Accumulator based (in your textbook)  Stack based (I added it)  Example: C = A + B; Accumulator LoadA AddB StoreC Halt Stack PushA PushB Add PopC Halt

More on Accumulator  C=A+B LoadA AddB StoreC Halt  C=A+B Load128 Add129 Store130 Halt  C=A+B

More on Stack  C=A+B PushA PushB Add PopC Halt  C=A+B Push128 Push129 Add Pop130 Halt  C=A+B

More complex statement (Accumulator) Example1: E = A+(B*C) + D Accumulator LoadB MulC AddA AddD StoreE Example2: E = A+(B*C) + (D*F) Accumulator LoadB MulC AddA StoreTMP LoadD MulF AddTMP StoreE

More complex statement (stack) Example1: E = A+(B*C) + D E = ABC*+D+ Example2: E = A+(B*C) + (D*F) E = ABC*+DF*+ Stack representation PushA PushB PushC Mul Add PushD Add PopE PushA PushB PushC Mul Add PushD PushF Mul Add PopE

Stack representation  What do u need to know?  How to solve equations represented in stack representation  How to translate stack representation to normal representation and vise versa  Example: - what is the result of 234+*562-*+? Note: answer = 34 - what is 234+*562-*+ in normal representation? Note: answer = (2 * (3+4)) + (5 * (6-2)) - what is 2*3+4*5 in stack representation Note: answer = 23*45*+