Download 10. Light, Multiplexing.pptx

Which of the transistors below are on?
9kΩ
A
5V
1kΩ
9kΩ
B
5V
1kΩ
-5V
C
6V
4V
D
2V
Submit your answer on menti.com with code 24 34 75
ENGR 40M, Lecture 10:
From logic gates to computers
Steven Bell
17 July 2016
Two levels of thinking about transistors
Voltage/circuit level
Transistor only "knows" voltages across its pins.
An NMOS turns on when VGS > Vth
A PMOS turns on when VGS < -Vth
Logic-level
Assume: NMOS source → Vdd, PMOS source → Gnd
Assume: Inputs are HIGH (1, Vdd) or LOW (0, Gnd)
Then:
An NMOS turns on when input is high
A PMOS turns on when input is low
Time taken on homework:
<= 1 hour
<= 2 hours
<= 3
> 3 hours
By the end of today, you should be able to:
Represent numbers using binary, with
2's complement for negative values
Explain the various datatypes in Arduino,
and predict overflow/underflow
Take a keyboard apart (and figure out how
it works).
Binary numbers
Convert the following decimal numbers to binary:
4, 19, 63, 256
Convert the following binary numbers to decimal:
10001, 10101, 00111, 11111111
overflow!
0000
1111
1110
1101
14
15
13
1011
1
0010
2
3
binary
integer
12
1100
0
0001
4
5
11
1010
10
9
1001
8
1000
0011
7
6
0100
0101
0110
0111
To write a negative number in 2's complement:
Write the positive number in binary
Flip all the bits (1→0, 0→1)
Add 1 (with all the appropriate carries)
To convert negative 2's complement to decimal,
Flip all the bits (1→0, 0→1)
Add 1 (with all the appropriate carries)
Write the number in decimal
unsigned overflow
1111
0000
0001
0010
15 0
1
2
14 -1 0 1
0011
1101
2
-2
3
13 -3
3
binary
unsigned
1100 12 -4
4 4 0100
signed
5
-5
5 0101
11
6
1011
-6
6
10 -7 -8 7
0110
7
9
1010
8
1110
1001
1000
0111
signed overflow
Convert the following decimal numbers to binary,
using 8-bit 2's complement:
-1, -12, -128, 4
Convert the following 8-bit 2's complement binary
numbers to decimal:
1000 0011, 0000 1011, 1111 1100
_
_
_
If you have 8 bits:
What is the largest signed number you can represent?
Smallest (most negative) signed number?
Casting from one data type to another doesn't
change the bits.
unsigned char x = 253;
char y = x;
print(y);
When you add more bits, the number
shouldn't change...
char x = -1;
int y = x;
print(y);
Building an adder
xkcd.com/571
Breaking break:
Keyboards!