6.189 Multicore Programming Primer
1.
Mini-Quiz #2 (01/12/2007) Solutions
This implementation is vulnerable to deadlock. For example, suppose we process
two votes concurrently: "Candidate 1 is better than candidate 2" and "Candidate 2 is
better than candi
Biased p-n junctions: current flow, cont.
The saturation current of three diode types:
IS's dependence on the relative sizes of w and Lmin
p(x), n(x)
p(xn)
Short-base diode, wn < Lh, wp < Le:
n(-xp)
x
#
-wp
-xp xn
wn
n2
Dh
qv AB / kT
i
J h (x n ) = q
e
-1
BJT Modeling: FAR models/characteristics
C
!FiF
or "FiB
iF
IES
B iB
+
vBE
C
iB
B+
"F # $
iC
=
iE
Defects
!
Design
!
Clif Fonstad, 10/6/09
"E
&
1
(1+ %E )
Dh N AB w B,eff
=
#
#
De N DE !w E,eff
IBS
vBE
E
(1$ %B )
(1+ %E )
!FiB
"F #
E
iC
(1$ %B ) & 1
=
iB
(
The Depletion Approximation: an informed first estimate of (x)
Assume full depletion for -xp < x < xn, where xp and xn are
two unknowns yet to be determined. This leads to:
$ 0
&
&#qN Ap
"(x) = %
& qN Dn
& 0
'
for
x < #x p
for #x p < x < 0
for 0 < x < x n
6.824 2006 Lecture 9: Memory Consistency (1)
Replicated data a huge theme in distributed systems
For performance and fault tolerance
Often easier to replicate data than computation (Hypervisor.)
Examples:
Replicated mailboxes and user info in Porcupine.
C
6.824 2006 Lecture 11: Memory Consistency (2)
Review from previous lecture:
We want to make it possible to write correct parallel/distributed
programs.
We assume different CPUs interact only through a storage system.
Memory, distributed shared memory, or
6.824 2006 Lecture 8: Tutorial on Cache Consistency and Locking
lecture overview
a tutorial to help you with labs 4 and 5
lab 4: locking for correctness with multiple servers
lab 5: caching for performance
overall goal:
ccfs-based distributed file system
6.824 2006 Lecture 7: Logging
What's the overall topic?
Atomic updates of complex data w.r.t. failures.
Today just a single system, we'll be seeing distributed versions
later.
Why aren't synchronous meta-data updates enough?
(from last lecture on file sys
2. [6 points]:
Consider the following Javascript code that returns twice the value of its argument x:
function double(x) cfw_
var y = x;
var cmd = "y=y+" + x;
eval(cmd);
return y;
Propose a design that extends lab 6 to safely support eval, such as in the
Language Definition Problem
How to precisely define language
L
Layered structure of l
d t t
f language d fi iti
definition
Start with a set of letters in language
Lexical structure - identifies words in language
structure
words
(each word is a sequenc
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Department of Electrical Engineering and Computer Science
6.012 MICROELECTRONIC DEVICES AND CIRCUITS
Answers to Exam 2 - Fall 2009
Problem 1: Graded by Prof. Fonstad
a) i)
Applying vGS > VT to an n-channel MOSFET accu