ECE 287 – Lecture 12 • Memory 1
Jul 30, 2015
ECE 287 – Lecture 12
• Memory 1
Announcements
• Next Quiz on Wednesday• Exam II – Nov 15th
AREA
SPEED
POWER
PRICE $$$
Starter…
Draw a circuit for the following:
while (A+B > 10)A--;
Memory
What is memory in a non technical context?What are some key words about memory?What happens in our brain?
Basic Latch
R
S
!Q
Q
Gated SR Latch
R`
S` Q
R
S
Clk
D Latch
Q
D
Clk
D Latch
clk
QD
D Latch
clk
D
Q
0 1 2 3 5 6 7 8 9 104
What does Q look like assuming no delays through gates?
Critical Path
Assume 1ns delay through all gates. Where’s the critical path
aff
clk
b
ff
clkc
o
Frequency
How fast can the circuit be clocked at?
1s is related to 1Hz
Frequency = 1/time
How many things per second?
Value Symbol Name Hz Terms s second 1 1 Hz10−1 s ds decisecond 1010−2 s cs centisecond 10010−3 s ms millisecond 1000 1 KHz10−6 s µs microsecond 1000000 1 MHz10−9 s ns nanosecond 1000000000 1 GHz10−12 s ps picosecond 1000000000000 1 THz10−15 s fs femtosecond10−18 s as attosecond10−21 s zs zeptosecond10−24 s ys yoctosecond
Problem Set
1. What is the output of the following circuit for each clock assuming the flip-flops are initialized as follows: ff0 = 1, ff1 = 0, ff2 = 0, and ff3 = 0. Does the sequence ever end or repeat? What might this be good for? What’s the critical path?
ff0 ff1 ff2 ff3
clk