Dave wrote:

>Great  Jeff.  Thanks for the explanation. 
>
>Why is a signal name required?  
>  
>
HAL requires unique names for each signal.  The reason is that there 
needs to be a way of connecting or disconnecting pins later on.  Of 
course, it also helps to see a useful name when you want to look at 
things in halscope, halmeter, or the HAL watch window.

>For instance:  Why doesn't this work:
>
>net outputpin inputpin    
>  
>
We used to have a command called linkpp which would let you do this:
linkpp pin1 pin2

It would create a signal named pin1, and connect both pin1 and pin2 to 
it, just like these commands would do:
newsig pin1
linksp pin1 pin1
linksp pin1 pin2

This would result in there being two things named pin1 - the pin itself 
and the signal it was connected to.  That seems a bit confusing at first 
(why is there a signal with a pin name?), and even worse later on when 
you want to add another pin to the net:
linksp pin1 pin3
Of course, you couldn't use "linkpp pin1 pin3", because there is already 
a signal named "pin1".

> From what I understand this is required:
>
>net signalname outputpin inputpin
>
> From what I have seen, if a signalname does not exist that can be used, 
>one must be created first
>before the net command will function.
>  
>
It might be useful shorthand for a user to be able to connect two pins 
without naming the connection.  It would be possible to auto-create a 
signal name (like sig001, sig002 ...) if you make a connection with no 
name specified, but I don't know that the development effort is really 
worth it, since the easy workaround is to simply supply a name with the 
net or newsig command.  This also lets you give the signal a name which 
means something to you:
net lube-level-critical parport.0.pin-03-in-not.

Note that the net command will create the named signal if it didn't 
already exist.

- Steve


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