Re: A83: Rom Calls


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Re: A83: Rom Calls




In a message dated 7/19/99 8:23:00 PM Central Daylight Time, 
jimbob_v@hotmail.com writes:

>  This doesn't matter too much unless you're worried about speed, but has 
>  anyone noticed that most of the rom calls for the TI-83 just refer to 
other 
>  addresses in the ROM, for example, the _clrlcdfull call is something like 
>  this:
>  
>  _clrlcdfull:
>    call $0031
>    ret
>  
>  If someone were to document all the PROPER addresses, this would speed 
each 
>  rom call by around 11 clock cycles I think..
>  It's not extremely important, but as I said, it would speed up execution.
>  
>  James Vernon
>  jimbob_v@hotmail.com

You cannot make "call _clrlcdfull" take less time by doing "call $0031" in 
your program. It is made that way because it has something to do with Rompage 
switching, to make sure it is on the correct page before executing the 
romcall you want. Perhaps for _clrLCDFull, it is located on Rompage 0, and 
that page doesnt get switched out (im guessing this incase a Restart 
Instruction occurs), so it may be possible to make the call to that address. 
The section of code you disassembled doesnt look like a complicated 
procedure, but other routines may have more to them. I would just use the 
romcalls to addresses TI provided in their include files... cya.

Jason_K