At 10:23 AM 09/19/98 +0200, you wrote:
>>In native mode the Z380 is compatible with the Z80. It can only execute
>>code in the first 64K of memory. Using a trick you can access data anywhere
>>in memory, but in the default configuration this is also restricted to the
>>first 64K.
>
>Not 100% true, even in native mode the Z380 ALU still 32 bits and by the
>way some coding tricks like:
>
>imagine you have to countdown the time of a game or what ever you want
>
> LD DE,(TimeCounter)
> LD HL,-2
> ADD HL,DE
>this wont give the good result on Z380
It will be correct in word mode. Width of data words can be set to either
16 (word mode) or 32 (long word mode) bits. This is independant of the
width of address words. I left it out of my explanation to keep it simple.
Native/extended mode and word/long word mode are two seperate things, and
only native/extended mode has something to do with addressing memory.
By the way, default mode is word mode, so after reset, Z380 will be Z80
compatible. Maybe except for the undocumented instructions, but all
official instructions will behave exactly like in the Z80.
>I'm not really interested in an MSX380 100% compatible with MSX, if I want
>to play MSX game or demos, I still have my MSX Turbo R or an MSX2. I think
>that the "new" MSX should free the power of the Z380 and other hardware to
>get a realy stong machine
In that case, you can better call it a new "MSX". But what is the use of
such a computer? In my opinion, it would be better to start programming the
PlayStation (PSX). It's cheap, reasonably fast and a lot of MSX people
already have one.
If you have to learn a new CPU, a new VDP and a new operating system for a
non-compatible Z380, why not learn an entirely new system?
I just fear that an incompatible Z380 would end up like the GFX9000: nice
hardware but very little software.
The reason MoonSound is a success is that it is not as determining for the
software as the GFX9000 is. If you support MUSIC/AUDIO and MoonSound, the
composer has to compose two versions of every song and you have to choose
from two replayers (which you don't have to write yourself). But other than
that, the entire program can remain unchanged.
For GFX9000, you not only have to draw new GFX (comparable with composing a
MoonSound version of a song), but you also have to make drastic changes in
your code (where MoonSound only required loading of a different replayer).
Z380 will be like the GFX9000: linear memory, 32-bit data and such are very
determining for your code. So it's not easy to code a program for both the
old and the new system. And history (GFX9000) tells us programmers are
reluctant to make something that only runs on the new system.
That is why compatibility is needed. Most of the time, the Z380 will
function as a very fast Z80. And in a few cases, special Z380 programs will
do wonderful things.
Bye,
Maarten
****
MSX Mailinglist. To unsubscribe, send an email to [EMAIL PROTECTED] and put
in the body (not subject) "unsubscribe msx [EMAIL PROTECTED]" (without the
quotes :-) Problems? contact [EMAIL PROTECTED] (www.stack.nl/~wiebe/mailinglist/)
****
