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*Concepts you may want to Google beforehand: scroll*
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**Goal: Scroll the screen when the text reaches the bottom**
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For this short lesson, open `drivers/screen.c` and note that at the
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bottom of `print_char` there is a new section (line 84) which checks
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if the current offset is over the screen size and scrolls the text.
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The actual scrolling is handled by a new function, `memory_copy`. It is
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a simpler version of the standard `memcpy` but we named it differently
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to avoid namespace collisions, at least for now. Open `kernel/util.c` to
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see its implementation.
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To help visualize scrolling, we will also implement a function to
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convert integers to text, `int_to_ascii`. Again, it is a quick implementation
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of the standard `itoa`. Notice that for integers which have double digits
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or more, they are printed in reverse. This is intended. On future lessons
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we will extend our helper functions, but that is not the point for now.
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Finally, open `kernel/kernel.c`. Initially, each line displays its line
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number. You can set a breakpoint on line 14 to confirm this. Then,
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the following `kprint`s force the kernel to scroll down.
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This lesson ends the coverage for the os-dev.pdf document. From now on, we'll
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follow [the OSDev wiki](http://wiki.osdev.org/Meaty_Skeleton) and
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other sources and examples. Thanks Prof. Blundell for that great document!
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