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scott wrote:
> Careful, go much further and you're going to end up designing a RAM chip
> :-)
Oh, I won't ever be designing a *chip*. ;-) But I might end up designing
RAM... (That way, at least *I* will know how it works.)
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On 5/20/2010 5:18 AM, Invisible wrote:
> (Seems to work in simulation...)
Unrelated, but tangential, How do you like LogiSim?
--
~Mike
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Mike Raiford wrote:
> Unrelated, but tangential, How do you like LogiSim?
Not very much.
I mean, it *works*, but that's about it. It's really hard work to *do*
anything with it. All gates default to having 5 inputs, no matter how
many times you change it back to 2. All devices default to East
orientation, no matter how many times you change it. Even just moving
part of the circuit to make some room is quite unecessarily difficult.
On top of that, the graphics look horrible, pin labels refuse to display
when you need to see them, it's quite hard to label anything properly,
and it spazzes out if you try to built a latch.
But apart from all that, it works perfectly. :-}
As if the problem of designing complex arrangements of logic wasn't hard
enough to start with...
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scott wrote:
> which is why LEDs don't light up at all below a certain voltage.
I read a book back in high school that talked about electronics and went all
the way from tubes to CMOS FETs, in sufficient detail that I even know *why*
on an atomic level LEDs don't light up below a certain voltage.
Was a really cool book. I wish I remembered the name of it. I was too young
at the time to realize it was exceptional.
--
Darren New, San Diego CA, USA (PST)
Ada - the programming language trying to avoid
you literally shooting yourself in the foot.
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>>> I think I resist any urge to comment on this. Other than "RTFM"
>>
>> I don't think electricity comes with a manual. Neither do ICs, usually...
>
> They do, they are called datasheets.
Datasheets aren't manuals. They assume that you already know what, say,
a Gated D-Latch is, and that you just want to know what its maximum
driving current is or something. If you *don't* already know what a
Gated D-Latch is, the datasheet will be of no use at all. You need
*real* instructions.
>> Hey, what do you *think* I've got a dad for? ;-)
>
> Hard to say, other than the obvious task of a father ;)
Damnit, I said don't answer that. :-(
> Have you ever looked at e.g.
> http://en.wikipedia.org/wiki/File:TTL_npn_nand.svg ?
1. What is this thing?
2. How does it help?
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Am 20.05.2010 19:14, schrieb Orchid XP v8:
>>> I don't think electricity comes with a manual. Neither do ICs,
>>> usually...
>>
>> They do, they are called datasheets.
>
> Datasheets aren't manuals. They assume that you already know what, say,
> a Gated D-Latch is, and that you just want to know what its maximum
> driving current is or something. If you *don't* already know what a
> Gated D-Latch is, the datasheet will be of no use at all. You need
> *real* instructions.
Well, typically the datasheets of stuff like D-latches come with a logic
table.
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On 20-5-2010 19:14, Orchid XP v8 wrote:
>>>> I think I resist any urge to comment on this. Other than "RTFM"
>>>
>>> I don't think electricity comes with a manual. Neither do ICs,
>>> usually...
>>
>> They do, they are called datasheets.
>
> Datasheets aren't manuals. They assume that you already know what, say,
> a Gated D-Latch is, and that you just want to know what its maximum
> driving current is or something. If you *don't* already know what a
> Gated D-Latch is, the datasheet will be of no use at all. You need
> *real* instructions.
Have you ever looked seriously at a datasheet?
Most datasheets contain a lot more information than just what it is.
Apart from just giving the pin layout, there is the logical function
(for logical ICs), specifications of allowed inputs and a description of
the outputs, often for complex ICs there are also typical application
and a small tutorial on the working of the thing.
E.g. take http://ww1.microchip.com/downloads/en/DeviceDoc/21805a.pdf
that covers everything from what a SAR is to an introduction to I2C.
What more would you want from a manual that isn't included in this??
The layout of datasheets is in general that they start with the things
you need to know if you already know what the IC does and the later
pages are increasing descriptive. Contrary to what you might expect, you
as a beginner should skip the technical data and go straight to the
later chapters in the datasheet.
>> Have you ever looked at e.g.
>> http://en.wikipedia.org/wiki/File:TTL_npn_nand.svg ?
>
> 1. What is this thing?
A (simplified) circuit of an actual NAND gate (e.g. the 7400). Hint:
read the title.
> 2. How does it help?
If you look at it you see why an open input will be seen as a logical 1.
Assuming you know how a transistor works of course. Let me guess: you
don't? :(
Sometimes I get the impression that you employ a top-down approach to
learning. A standard education path generally begins with the basics and
then slowly gets to the more complicated issues. This concept is already
very old and indeed perhaps too old and in dire need of replacement. I
admire your attempt to revolutionize education and will be following
this experiment with the utmost of interest.
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On 20-5-2010 6:48, Kenneth wrote:
> andrel <byt### [at] gmail com> wrote:
>
>> I think I resist any urge to comment on this. Other than "RTFM" and "buy
>> any 'electronics for dummies book'" before embarking on such a project.
>
> A good place to start would be Don Lancaster's two books, TTL COOKBOOK and CMOS
> COOKBOOK. Wonderfully easy to read and comprehend. My copies are *old*,
> dog-eared and marked up with my comments--I basically taught myself digital
> electronics and logic from them, starting from scratch. The best books on these
> subjects that I've ever run across. (I see that they are still available at
> Amazon.)
Ok, Andy, here is the deal: we trust Ken in this, you put one of these
books on your Amazon Wish list and you give me a link to that wish list.
In exchange, after you received it, you read it and you stop asking
questions that are answered in the book. Remember: Ken has also a copy.
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>> 2. How does it help?
>
> If you look at it you see why an open input will be seen as a logical 1.
> Assuming you know how a transistor works of course. Let me guess: you
> don't? :(
>
> Sometimes I get the impression that you employ a top-down approach to
> learning. A standard education path generally begins with the basics and
> then slowly gets to the more complicated issues. This concept is already
> very old and indeed perhaps too old and in dire need of replacement. I
> admire your attempt to revolutionize education and will be following this
> experiment with the utmost of interest.
I was going to suggest he learnt about transistor basics (including the
analogue analysis of simple transistor circuits) before embarking on a
project using them - but you said it much better than I could :-)
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>> Datasheets aren't manuals. They assume that you already know what,
>> say, a Gated D-Latch is, and that you just want to know what its
>> maximum driving current is or something. If you *don't* already know
>> what a Gated D-Latch is, the datasheet will be of no use at all. You
>> need *real* instructions.
>
> Have you ever looked seriously at a datasheet?
Gee, let me see now. I believer there are at least 4 linked from this
thread alone. So that would be, um... yes.
> Most datasheets contain a lot more information than just what it is.
> Apart from just giving the pin layout, there is the logical function
> (for logical ICs), specifications of allowed inputs and a description of
> the outputs, often for complex ICs there are also typical application
> and a small tutorial on the working of the thing.
> E.g. take http://ww1.microchip.com/downloads/en/DeviceDoc/21805a.pdf
> that covers everything from what a SAR is to an introduction to I2C.
> What more would you want from a manual that isn't included in this??
> The layout of datasheets is in general that they start with the things
> you need to know if you already know what the IC does and the later
> pages are increasing descriptive. Contrary to what you might expect, you
> as a beginner should skip the technical data and go straight to the
> later chapters in the datasheet.
The datasheet for the 7400 is 1 page. It tells you the maximum voltages
and currents, a few time constants, and that's literally *it*.
As I say, it's not a manual. It assumes that you already *know* what a
NAND gate is (which fortunately I do).
>> 2. How does it help?
>
> If you look at it you see why an open input will be seen as a logical 1.
> Assuming you know how a transistor works of course. Let me guess: you
> don't? :(
I have no idea how or why transistors work. But then, the entire _point_
of a logic gate is that it doesn't matter _how_ it works. It's a black
box. It implements a logical function. That should be all you need to know.
> Sometimes I get the impression that you employ a top-down approach to
> learning. A standard education path generally begins with the basics and
> then slowly gets to the more complicated issues. This concept is already
> very old and indeed perhaps too old and in dire need of replacement. I
> admire your attempt to revolutionize education and will be following
> this experiment with the utmost of interest.
Apparently I'm missing your point...
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