Olin Lathrop wrote:
> Never ever set the configuration bits from this menu.  Always specify them
> in the code else they may not end up in the HEX file.  Use the configuration
> bits menu to verify that the source code is setting the bits as you
> intended.
>   
That's good to know!  I might assume you would want them in the code so 
that you (and others) know what was done at some future date.

>> I'm
>> new enough at this to not know what needs to be set (ie _MCLRE_ON &
>> _CP_OFF &  _WDT_OFF) as I might have done with a 16F84.
>>     
>
> There is no shortcut with the config bits.  You have to go thru the manual
> and decide which way you want every one of them.  In general, leave the MCLR
> pin in its MCLR role, for starters you can use the internal oscillator to
> get the first LED blinking, always disable PGM, keep the watchdog off, and
> don't turn on any of the code or read or write protection.
>   
I'm certainly not against reading the datasheet.  I do want to 
understand what the settings are for and how they might apply for what 
I'm trying to do - even if it's as simple as lighting an LED.  I think 
it might be in my best interest to sacrifice an ink cartridge and print 
out all 400+ pages at least for my first 18F chip. 
>> CONFIG OSC=LP ;I'll use a 20MHz crystal at OSC1 & OSC2
>>     
>
> For 20MHz you will need HS mode.  LP is "low power", which uses a weaker
> drive that won't work at 20MHz.
>   
I overlooked that setting despite looking at the datasheet.  :-)  I see 
I can also choose the internal oscillator, which is probably adequate 
for lighting and flashing LEDs.  Once I get a basic program working, I 
think I'll want to play around with various configurations to see if it 
affects the operation as my interpretation of the datasheet.

> If you're going to be sticking to the 18F for a while, get a handful of
> 10MHz crystals.  That way you can run the PIC at its maximum speed of 40MHz
> using the 4x PLL mode.
>   
That's another mode I'll still need to read about.

>> start
>> CLRF PORTB ;initialize port B
>>     
>
> Labels start in column 1 and opcodes in column 2 or greater.
>
> Also, there are various analog peripherals multiplexed on many of the pins.
> In general, every pin that could be analog wakes up that way.  You should
> probably just disable the A/D (and comparator ?) up front, then turn it on
> in a module for that purpose later if you are using it.  Just clearing TRIS
> isn't necessarily enough to make a pin a usable output.
>
>   
To my credit, I did have the example in columns as you suggest.  I think 
the plain text format of my post may have removed any tabs. 

Part of the problem I see as a beginner is not knowing about all the 
various modes of operation, such as A/D, comparator, etc.  While I 
certainly agree that the datasheet is an indispensable reference, at 400 
pages it's hard to know what all needs to be done, especially when 
starting out.  Such and such a mode is possible, but is it necessary to 
enable / disable / don't care for what I'm trying to do?  Such questions 
are probably answered, but I need to know such capabilities exist in the 
first place.
>> I receive
>> errors such as:   Executable code and data must be defined in an
>> appropriate section.  I'll need to learn what that means.
>>     
>
> You need to read about the various assembler directives in the
> MPASM/MPLIB/MPLINK manual.  In this case you are missing a CODE directive,
> but you need to read that manual anyway because there are a lot more
> directives you will bump into.
>
>   

Now that is something I'll look at!  I know in my failed example, I used 
binary in the code. I'm sure that could just as easily be expressed in 
hex, though I find the binary easier at a glance to see which setting is 
affected.


Thank you for the help and suggestions.

Joe

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