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"PRINT AT" vs #BACKTAB


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PRINT AT uses the same card number as #backtab. So these are equivalent:

 

        PRINT AT 25,$010f

 

        #backtab(25) = $010f

 

PRINT AT is a convenience statement to simplify the writing of text to screen. Also allows to display easily numbers.

 

It admits strings and keeps the current cursor position so you can do multiple PRINT statements without setting the position and color. It also allows you to "forget" the GRAM card format and GROM codes for letters/digits.

 

If you are using PRINT AT to draw a few cards on screen, then it is faster to use #backtab, because PRINT keeps an extra cursor variable to keep the next position on screen.

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Both PRINT AT and #backtab accomplish the same thing: writing to the memory array between $200 and $2ef, where the Intellivision SITC fetches background graphics from on subsequent video frames.

 

As Oscar said, be aware that PRINT is more straightforward but at the expense of speed.  Just trying to draw seven three-digit numbers within a single video frame using PRINT caused a Stack Overflow, forcing me to use #backtab instead.

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