[A83] Re: Ti-83+ jump

To: assembly-83@lists.ticalc.org
Subject: [A83] Re: Ti-83+ jump
From: Peter-Martijn Kuipers <hyper@hysoft-automation.com>
Date: Sun, 11 Nov 2001 12:23:07 +0100 (CET)
In-Reply-To: <F195ArGvnCjnZS08i7M000260e0@hotmail.com> from "The one and only SUCKER ..." at Nov 11, 2001 10:41:02 AM
Reply-To: assembly-83@lists.ticalc.org


The Z80 Microprocessor has addressing space for 65536 (Or 10000h) memory 
addresses.
The TI-83 uses only these addresses, so you can jump/call to any of them
directly.

The Ti83+ however, uses more (flash!) memory than the 65536 locations, so
a technique called memory mapping is done.

In this technique, a bigger meory part is divided in chunks of 4000h bytes...
(16 kB)
these chunks are called "pages".
A page can be loaded into memory area 4000h - 7FFFh.
if you'd do a jump/call to 4500h for example, you could end up on any 
flash pages that is currently loaded, which may not be necessarily 
be the flash page your desired routine is on.

Bcall makes sure the right flash page is loaded before attempting the call,
so you get the right page always.


 
> 
> Why do we need to do a bjump/bcall with a ti-83+ (and SE?)??
> Isn't there a way to just do a jp/jr or a call xxxx??
> 
> SUCKER
> 
> _________________________________________________________________
> Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp
> 
> 
>

References:

[A83] Ti-83+ jump

From: "The one and only SUCKER ..." <sucker_pvn@hotmail.com>

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