BCD as well as HEXADECIMAL as well a BINARY or OCTAL and so on,
is a different way of looking at individual grouping of the same bits.
Much like we have the same alphabet in German as in English, but
we can express the same notion in a different arrangement of letters.
The Binary Codes of above have evolved during the dark ages of the computer
when coding in Assembly (a high level interpretation of Machine Code) was
king.
Computers - at their core- do not understand language as we do. They know
only
- in what we call Positive Logic- representations of Voltage Present ( a
"1")
or Voltage Absent ( a "0").
Strings of many "1" and "0" make up computer words used to program it.
When you say that your PC is 64 bit you actually say that the programming
word
of the computer is 64 1s and 0s (bits) in length. This definition is one of
many as different processor manufacturing have their own deviation from the
standard :)
Thus, OCTAL, HEX and BINARY is the different view of the same number of
bits.
Here is an 4 bit (for simplicity) example:
Decimal Binary HEX OCTAL
0 0000 0000 000
1 0001 0001 001
2 0010 0010 010
3 0011 0011 011
4 0100 0100 100
5 0101 0101 101
6 0110 0110 110
7 0111 0111 111
8 1000 1000 000 Observe here the
OCTAL roll over
9 1001 1001 001
10 1010 A 010 Observe HEX values
represented by alphabet letters
11 1011 B 011
12 1100 C 100
13 1101 E 101
14 1110 D 110
15 1111 F 111
A Pull-Up is a resistor that is connected between the Positive (usually)
voltage and an active node of a network. It provides a constant voltage to
this node even the network's inputs are floating or in high impedance.
A Pull-Down resistor is much as above but it is connected to the ground thus
pulling the node to the ground.
Just FYI :)
Hope I answered all your questions. If not, please write in private so we
will not disturb the TowerTalk world.
Alex
===================================
If we can accept the notion that GUNS are
the killers and not the people, why is it that
we can not accept the idea that CARS are
the speeders and not the drivers?
Alex, trying to understand the world around.
==================================.
----- Original Message -----
From: "Chris BONDE" <ve7hcb@rac.ca>
To: "alex" <alex@sandlabs.com>
Cc: <towertalk@contesting.com>; "Pete Smith" <n4zr@contesting.com>
Sent: Friday, December 21, 2001 9:27 PM
Subject: Re: [TowerTalk] Decoding BCD with passive circuit
>
> I would like to learn more. However, I take umberance with "Binary Coded
> Decimal is same as HEX only it rolls over at "9" "
> Decimal Heximal Octanal ae all differnet systems. I donot know what the
> same as is. There are differnent base systems. I remember some of this
> enought to think that the quated part is in error.
>
> However, the gist of the message is good. I further have not learned the
> "new" stuff and would like to do so.
>
> SO what the heck is a pull up or a pull down risistance. (Not thinking of
> anything sexual)
>
> Chris opr VE7HCB
>
> At 05:40 AM 2001-12-22 -0500, alex wrote:
>
> >BCD or Binary Coded Decimal is same as HEX only it rolls over at "9"
> >Thus, you have to decode 9 combinations of 4 bits. Not hard but hardware
> >intensive as diodes take a lot of space. You need pull-up and pull-down
> >resistors to
> >create "AND" and "OR" gates.
> >An elegant approach is to use a PIC micro to do the stuff you need. It
costs
> >a dollar or two and the development environment is free.
> >
> >If you need help, I can help set you up :)
> >
> >If you have a FAX, I can send you a diagram for the diode decoder you
want
> >to have :)
> >
> >Alex
> >
> >
> >===================================
> >If we can accept the notion that GUNS are
> >the killers and not the people, why is it that
> >we can not accept the idea that CARS are
> >the speeders and not the drivers?
> >
> >Alex, trying to understand the world around.
> >
> >==================================.
> >
> >----- Original Message -----
> >From: "Pete Smith" <n4zr@contesting.com>
> >To: <towertalk@contesting.com>
> >Sent: Friday, December 21, 2001 3:15 PM
> >Subject: [TowerTalk] Decoding BCD with passive circuit
> >
> >
> > >
> > > I'm told that this can be done with a diode matrix to power switching
> > > relays. Can anyone point me to a reference, preferably on the web,
for a
> > > basic circuit? Application would be in remote antenna switching.
> > >
> > > Thanks!
> > >
> > > 73, Pete N4ZR
> > >
> > > The revised World Contest
> > > Station Database
> > > is online at www.pvrc.org
> > >
> > >
> > >
> > >
> > >
> > > AN Wireless Self Supporting Towers are now available! Windloading
tables,
> > > foundation diagrams and charts, along with full details are now at the
> > > AN Wireless Web site: http://www.ANWireless.com
> > >
> > > -----
> > > FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> > > Submissions: towertalk@contesting.com
> > > Administrative requests: towertalk-REQUEST@contesting.com
> > > Problems: owner-towertalk@contesting.com
> > >
> >
> >
> >AN Wireless Self Supporting Towers are now available! Windloading
tables,
> >foundation diagrams and charts, along with full details are now at the
> >AN Wireless Web site: http://www.ANWireless.com
> >
> >-----
> >FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> >Submissions: towertalk@contesting.com
> >Administrative requests: towertalk-REQUEST@contesting.com
> >Problems: owner-towertalk@contesting.com
>
>
> AN Wireless Self Supporting Towers are now available! Windloading tables,
> foundation diagrams and charts, along with full details are now at the
> AN Wireless Web site: http://www.ANWireless.com
>
> -----
> FAQ on WWW: http://www.contesting.com/FAQ/towertalk
> Submissions: towertalk@contesting.com
> Administrative requests: towertalk-REQUEST@contesting.com
> Problems: owner-towertalk@contesting.com
>
AN Wireless Self Supporting Towers are now available! Windloading tables,
foundation diagrams and charts, along with full details are now at the
AN Wireless Web site: http://www.ANWireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
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