Re: A85: ROM vs. RAM


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Re: A85: ROM vs. RAM




You can ld FROM the ROM, just not to it.  Basically ROM is permenant and
unchangeable, RAM can change millions of times.

At 02:09 AM 2/25/98 -0500, you wrote:
>
>> Now, I kinda know the difference between the two, but could someone please
>> help me out?  You jp and ld in the RAM, but call to the ROM, right?  I'm
>> just making sure.  Is it possible to ld to the ROM?  I'm relatively knew to
>> assembly, so please bear with me.  Thanks!
>
>RAM stands for Random Access Memory. You can do anything with it
>whenever. ROM stands for Read Only Memory. You can only read what
>has been burned on it. You can jp and ld and call RAM. You can jp
>and call ROM. You cannot load the ROM with anything. If you try,
>nothing will happen. When you jp, it's like goto in basic. Whatever
>program jp'ed stops execution and will not be started again unless
>some other program jp's or calls back. Call will call it as a sub-
>program. As soon as the subprogram is done and ret's, the original
>program resumes where it left off. ROM was written by TI and is the
>built in programming that tells the calculator how to be a calculator.
>It also contains data and executibles that never change after the
>calculator is made. The RAM is used for variables, storage of infor-
>mation that changes (like settings), and for user installed programs.
>User programs in RAM can be called or jp'ed just like the built-in
>ROM routines.
> 
---
 Jim Reardon
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