[A83] Re: Me so curious
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[A83] Re: Me so curious
--- Peter-Martijn Kuipers <hyper@hbyte.net> wrote:
>
> Since nobody seens to answer your questions, I will
> try to ;-)
>
>
> > In the few months I've been assembly programming
> on my
> > TI-83+ SE, I have a few questions:
> >
> > 1. Detached Solutions says that the 83+ can only
> > execute out of certain memory areas. What are
> these
> > areas?
>
> They've put it a little simply. I'll try to
> elaborate:
>
> The TI-83+ has more memory than the chip can
> address, so
> different pages of memory can be put into
> different cpu-addresses...
> 4000h - 7FFFh is usually the space flash-apps and
> flash memory pages
> are mapped to
> 8000h - BFFFh is normally mapped to RAM-memory
> page 1
> C000h - FFFFh is normally mapped to RAM-memory
> page 0
>
> once an ASM program is about to be executed, it is
> shifted down to begin
> at address 9d95h which is on page 1.
>
> There is a hardware hack that resets the
> calculator once a program
> executes on ram page 0.
> this means that a program's executable area can't
> (without special
> tricks) be larger than C000h - 9d95h , about 8.3
> kb if I remember
> correctly.
In that case, more questions:
1. What if page 0 was mapped to 4000h? Would it run?
2. What if a flash page was mapped to C000h? Would it
run?
3. What is this special trick? Copying code from page
0 to page 1?
4. Why is the page starting at 8000h also mappable? Is
it used by ROM functions that access other FLASH pages
(ie _flashtoram)?
>
> > 2. If _flashtoram with a=0 really copies from ram
> to
> > flash, how do you specify the page?
>
> the 83+ SDK doesn't mention this feature, where
> did you get this
> info?
The "Plasma" Ion-compatible shell says in its code:
;Undocumented function of flashtoram. If a=0 it copies
form Ram! Me like this:)
;Thank you joe f[lint] for discovering this.
However, it doesn't seem to use this function. I guess
I should be asking Joe Flint, or Brandon Engleberth
(the other author of Plasma). Does anyone know how to
directly write to Flash without going through the
TI-OS?
>
>
> > 3. Why is there no FlashApp shell for the TI-73?
> Or is
> > there and it's not on ticalc.org? (I had one a
> couple
> > years ago in school, which is why I'm asking.)
>
> perhaps it's not a thing mostly needed, If I
> remember correctly,
> the 73 can't normally execute assembly programs,
> just flash-apps
> (or am I totally wrong here)
> most shells provide extra functionality for
> asm-programs, unless they're
> crap, so, it's probably not needed
What Jimmy Pardey said: The app executes assembly code
stored in a program.
>
> > 4. I can't remember :-) Ah well, I'll ask when I
> do.
=====
"The consequences of our actions are always so complicated,
so diverse, that predicting the future is a very difficult
business indeed." -Albus Dumbledore
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