Flip Flops

Discussion in 'Electronic Basics' started by Neutron, Sep 15, 2005.

1. NeutronGuest

I have a comp sci degree, and something that was never explained were flip
flops.
I never understood on a chip how switching occurs with no moving parts, no
this is not a troll but a genuine newbie to electronics question, which as I
get involved with am beginning to really enjoy, having just built a working
kit. The course lectures never went near the electronics side of things, the
closest we got were logic gates.

TIA,

2. Andrew HolmeGuest

Since you know about logic gates, you might start by looking at the
basic SR flip flop -

3. Randy DayGuest

Chips use logic gates in a 'cross-coupled'
configuration to hold each other high and low
until the inputs change.

Googling 'flip flop gate tutorial' found:

http://www.play-hookey.com/digital/
http://www.play-hookey.com/digital/rs_nand_latch.html

You can trace the logic levels through the
gates to see how they reinforce each other's
logic state until an input change occurs.

HTH

4. John LarkinGuest

Good grief! How high up the abstraction stack did they start?

How can people teach computer "science" and not explain how a computer
works? That would be like teaching physics and ignoring the simple
stuff like force and momentum.

John

6. Bill BowdenGuest

I never understood on a chip how switching occurs with no moving parts

There is a toggle flip flop, using a couple transistors, with

http://ourworld.compuserve.com/homepages/Bill_Bowden/page9.htm#toggle.gif

It doesn't use any ICs, but does have one moving part, a pushbutton
switch to toggle the thing, but you could use a short negative pulse
from some other source to replace the switch, thus eliminating all
moving parts.

-Bill

7. dbernat32Guest

John:

Computer Science is a specialization of Mathematics, in particular linear algebra, combinatorics, graph theory, and other discrete math and related topics. It involves generating mathematical algorithms which solve problems efficiently (or not). It would naturally start very high up with "I have a computer that can execute such and such instructions and has such and such storage space. How do I solve a problem with a series of these instructions?" One doesn't need to know that SRAM uses logic gates and DRAM uses capacitors or how to simplify a K-Map in order to create a series of computer instructions that inverts a matrix.

People don't need to understand a BCD->7seg decoder in order to read their digital watch, do they?

And really, considering that most Computer Engineering/Electrical Engineering programs don't even talk about digital design until junior or senior year, you can hardly expect a Computer Science program to get anywhere near that point.

--dbernat32

8. John LarkinGuest

Oh, *that* explains why I'm seeing so little viable competition
lately. Suits me just fine.

John

9. Kitchen ManGuest

Do the CE/EE programs you are familiar with talk about how to set
graduated introduced digital basics as a Freshman class, and I know
how to use a newsreader. There may be a logical correlation.

10. Jasen BettsGuest

on the chip electrons are the moving parts.

an N channel FET works by electrons in one place (called the gate) repelling
electrons in another place (called the channel) and stopping them from flowing
past.

so here an abundance of electrons in one place causes a lack of electrons in
a second place... and vice versa, this is the basis of the switching that's
used to build flip-flops and other logic devices.

Bye.
Jasen

11. dbernat32Guest

Kitchen Man:

The basics are taught earlier, yes. Logics gates and what-not. How one combines BJTs into an inverter or NAND gate and why it works, that is taught much later.

As for word-wrap, not to start a flame war but, get a MIME compliant newsreader. MIME has existed now for a long time. You would then notice that my previous message and this one are encoded in "quoted-printable". A MIME compatible reader will properly display such a message and perform word-wrapping automatically.

I, personally, enjoy choosing the line length that pleases me the most. I do not always like the forced word-wrapping that you would suggest I use.

--dbernat32

13. dbernat32Guest

Usenet started in 1979. Times have changed a little since then. Most of the Usenet standard guides were written in the 90's. Most people have MIME compatible newsreaders; the few that don't should get one.
If people never question the standards, nothing changes, especially changes for the better.
I repeat that I enjoy choosing a line length myself, not one chosen by the poster or his/her newsreader. "Quoted-printable" encoding allows for this.

--dbernat32

14. Michael A. TerrellGuest

Who says that it needs to change? If you don't like the way Usenet
works, there are thousands of code bloat filled PHP based forums you can
move to. Not everyone has a choice of how they read newsgroups. Some
are blind and have to use software to hear the page. Others can't use
newer software, and can't buy a new computer, while others are using
someone else's computer.

On the other hand there are plenty of self centered jerks who want
everyone to change to please them.

15. JeffMGuest

Most people have MIME compatible newsreaders;
You'll notice that he top-posts as well.
I think you found the proper word.

16. Fred AbseGuest

What is really needed is a newsreader that converts top posting ;-)

17. Michael A. TerrellGuest

I'd rather have one that sends a nasty shock to top posters when they
click on "SEND". ;-)

18. Jasen BettsGuest

0ne of the tasks set me in freshman CS year was implementing word wrap.
But you're right the lack of wrap is annoying,

Bye.
Jasen

19. Rich GriseGuest

OK, I'll start the flame war.

USENET is an ASCII medium. It is designed for text. A _real_ newsreader
sends and receives ASCII text. Binaries are a fairly recent addition, and
all these gyrations that they have to go through to do tricks on USENET
are from scriptkiddies who like whiz-bang, but wouldn't know netiquette if
it jumped up and bit them in the ass.

And about the rudest thing you can _possibly_ do when someone offers you
a suggestion to improve your posting style, is to demand that _they_
get a different newsreader to accommodate _your_ shortcomings.

http://www.catb.org/~esr/faqs/smart-questions.html

Thanks,
Rich

20. Rich GriseGuest

No, people who suggest that others "should" use something that suits
_your_ rudeness and block-headedness, should **** off and die.

Thanks,
Rich