1. Introduction to Computer Engineering
CS/ECE 252, Fall 2016
Kai Zhao
Computer Sciences Department
University of Wisconsin – Madison

2. Releasing Untested Software
Boss pressuring you to release software
Every day delay is $1 million in sales
Is it okay to release software not fully tested?
What if it’s a medical device?
A number of patients receive
up to 100x the intended dose
of radiation therapy in
died as a direct
results and 21 died the
following years
A number of patients receive up to 100x the intended dose of radiation therapy in

3. Ethics Wrapup Laws Ethics Discussion
Set of rules with civil and/or criminal penalties
can be enforced by governmental bodies
Ethics
Set of standards, usually voluntary
Discussion
Usually, no clear right and wrong
Choose between competing interests

4. Recap Story behind Quote of the Day Quote of the Day:
“It is a good thing for an uneducated man to read books of quotations.”
-- Sir Winston Churchill

5. Chapter 1: Abstraction and Complexity
Abstraction helps us manage complexity
Complex interfaces
Specify what to do
Hide details of how
Application Program
CS302
Operating System
CS537
Compiler
CS536
Machine Language (ISA)
CS/ECE354
Goal: Use abstractions yet still understand details
Computer Architecture
CS/ECE552
Scope of this course
Digital Design
CS/ECE352
Electronic circuits
ECE340

6. Chapter 2: Number Representation
2’s complement representation
-23 22 21 20 1 2 3 4 5 6 7
-23 22 21 20 1 -8 -7 -6 -5 -4 -3 -2 -1

7. Chapter 2: Hexadecimal and Operations
Hexadecimal table
Addition
Binary
Hex
Decimal
Unsigned
2’s complement
1000 8 -8
1001 9 -7
1010 A 10 -6
1011 B 11 -5
1100 C 12 -4
1101 D 13 -3
1110 E 14 -2
1111 F 15 -1
Binary
Hex
Decimal
0000
0001 1
0010 2
0011 3
0100 4
0101 5
0110 6
0111 7
(104) (-10)
(-16) + (-9)
(98) (-19)

8. Chapter 3: Transistor Gate Supply Voltage Output P-type transistor
Ground
N-type transistor
Gate
Behavior 1
Closed Output=0
Open
Output=Z
Gate
Behavior
Closed Output=1 1
Open
Output=Z

9. Chapter 3: Building logic gates from transistors
NOR gate A B C 1

10. Chapter 3: implementing truth tables w/ logic gatesD 1
1. AND combinations that yield a "1" in the truth table.
2. OR the results of the AND gates.

11. Chapter 3: Memory
R is used to “reset” or “clear” the element – set it to zero.
S is used to “set” the element – set it to one.
If both R and S are one, out could be either zero or one.
“quiescent” state -- holds its previous value
note: if a is 1, b is 0, and vice versa 1 1 1 1 1 1 1
out
out 1 1

12. Chapter 3: Finite State Machine
A description of a system with the following components:
A finite number of states
A finite number of external inputs
A finite number of external outputs
An explicit specification of all state transitions
An explicit specification of what causes each external output value.

13. Chapter 4: Von Neumann Model

14. Chapter 5: LC-3 ISA

15. Chapter 6: Programming via Iterative Refinement
Decompose task into a few simpler subtasks.
There are three basic ways to decompose a task:

16. Chapter 6: Debug by Tracing
execute
instruction
sequences
set/display
registers
set/display
memory
set breakpoints

17. Chap7: Char Count in Assembly Language (1 of 3);
; Program to count occurrences of a character in a file.
; Character to be input from the keyboard.
; Result to be displayed on the monitor.
; Program only works if no more than 9 occurrences are found.
; Initialization
.ORIG x3000
AND R2, R2, #0 ; R2 is counter, initially 0
LD R3, PTR ; R3 is pointer to characters
GETC ; R0 gets character input
LDR R1, R3, #0 ; R1 gets first character
; Test character for end of file
TEST ADD R4, R1, #-4 ; Test for EOT (ASCII x04)
BRz OUTPUT ; If done, prepare the output

18. Chap7: Char Count in Assembly Language (2 of 3);
; Test character for match. If a match, increment count.
NOT R1, R1
ADD R1, R1, R0 ; If match, R1 = xFFFF
NOT R1, R1 ; If match, R1 = x0000
BRnp GETCHAR ; If no match, do not increment
ADD R2, R2, #1
; Get next character from file.
GETCHAR ADD R3, R3, #1 ; Point to next character.
LDR R1, R3, #0 ; R1 gets next char to test
BRnzp TEST
; Output the count.
OUTPUT LD R0, ASCII ; Load the ASCII template
ADD R0, R0, R2 ; Covert binary count to ASCII
OUT ; ASCII code in R0 is displayed.
HALT ; Halt machine
Do comparison by adding not

19. Chapter 9.2 Subroutines
; CountChar: subroutine to count occurrences of a char CountChar ST R3, CCR3 ; save registers ST R4, CCR4 ST R7, CCR7 ; JSR alters R7 ST R1, CCR1 ; save original string ptr AND R4, R4, #0 ; initialize count to zero CC1 JSR FirstChar ; find next occurrence (ptr in R2) LDR R3, R2, #0 ; see if char or null BRz CC2 ; if null, no more chars ADD R4, R4, #1 ; increment count ADD R1, R2, #1 ; point to next char in string BRnzp CC1 CC2 ADD R2, R4, #0 ; move return val (count) to R2 LD R3, CCR3 ; restore regs LD R4, CCR4 LD R1, CCR1 LD R7, CCR7 RET ; and return

20. Chapter 8: I/O CPU Control/Status Registers Data Registers
CPU tells device what to do -- write to control register
CPU checks whether task is done -- read status register
Data Registers
CPU transfers data to/from device
Device electronics
performs actual operation
pixels to screen, bits to/from disk, characters from keyboard
Graphics Controller
Control/Status
CPU
Electronics
display
Output Data

21. Chapter 9.1 TRAPs Code Equivalent Description HALT TRAP x25
Halt execution and print message to console. IN
TRAP x23
Print prompt on console, read (and echo) one character from keybd. Character stored in R0[7:0].
OUT
TRAP x21
Write one character (in R0[7:0]) to console.
GETC
TRAP x20
Read one character from keyboard. Character stored in R0[7:0].
PUTS
TRAP x22
Write null-terminated string to console. Address of string is in R0.