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Introducing the Instruction Set Part 3 - Intellivision Wiki

Introducing the Instruction Set Part 3


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From Intellivision Wiki

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That runs very fast, but it takes up a ton of ROM.  Also, it clears the screen only once.  What if you want to clear the screen many times throughout your program, perhaps from different places?  You really don't want to copy this same code everywhere you need to clear the screen.  That's where branches come in.<BR/><BR/>
That runs very fast, but it takes up a ton of ROM.  Also, it clears the screen only once.  What if you want to clear the screen many times throughout your program, perhaps from different places?  You really don't want to copy this same code everywhere you need to clear the screen.  That's where branches come in.<BR/><BR/>
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Branches tell the CPU to start executing at a different location, rather than barreling forward.  Unconditional branches and jumps tell the CPU to always jump to that location.  Conditional branches tell the CPU to jump to a new location <I>if some condition is true.</I>  These let you skip pieces of code, or repeat them a number of times.  Jumps to subroutine tell the CPU "go do this and come back when you're done."  The following sections explore these concepts a little more closely.<BR/><BR/>
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Branches tell the CPU to start executing at a different location, rather than barreling forward.  Unconditional branches and jumps tell the CPU to always jump to that location.  Conditional branches tell the CPU to jump to a new location <I>if some condition is true.</I>  These let you skip pieces of code, or repeat them a number of times.  Jumps to subroutines (also known as "calls") tell the CPU "go do this and come back when you're done."  The following sections explore these concepts a little more closely.<BR/><BR/>
= Branches and Labels =
= Branches and Labels =

Latest revision as of 04:57, 18 November 2011

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