Re: TI-86 speed
[Prev][Next][Index][Thread]
Re: TI-86 speed
On Sat, 30 Aug 1997 08:32:24 -0500, Adrian <peregrine@jwp.bc.ca>
wrote:
>I just got an 86 and noticed it runs programs significantly slower than
>the 85. Why??? It has the same processor. Is there anything I can do to
>correct this?
>TIA
>
>--
> | HurghwI' - Adrian
> _|\_ http://www.jwp.bc.ca/peregrine
> / / \ \ email - peregrine@jwp.bc.ca
> ,-\\ //\__ PGP ID 0x83FE3088
>/ __\\//___/ mIS yIjach, 'ej veS
>|/ `----` targhmey tIQeyHa'choHmoH!
>
>
The 85 and 86 are essentially the same, except of course the size of
RAM. essentially, you could call it the 85, ROM v11.0, with 4 times as
much RAM. However, the Z80 can only access a 16-bit offset in memory.
The first 32k is for ROM, and the last is for RAM. On the TI-85 *AND*
the TI-86, there is more than 32k of rom. Whenever the ti-8x needs to
access some code in ROM not currently in the 32k 'page', it changes
the current rom 'page', and goes again. This is fairly fast. However,
it does cause a minor slowdown. This happends in both the 85 and 86,
so the problem isn't there. However, the 86 RAM is *ALSO* too big for
it's 32k allotted space. so, the 86 pages it's RAM, and the 85, which
has just 32k memory, which fits into the allocated memory range
$8000-$FFFF, does not.
Furthermore, due to the way variables are stored, *whenever* you
access a variable, your calc needs to 'scan' through the variable name
data blocks. Think of it as a harddrive: whenever you access a file,
dos checks in the FAT where, then retrieves the data. Ie: the more
variables, the more slowdown. NB: This does not affect assembly
programs, unless of course they also use variables. in the 86, you
have 128k. 4 times as much memory to put stuff in. Usually that means
you have loads more variables.
The solution:
delete whatever you don't need.
References: