On Sat, 21 Aug 1999 20:33:35 +0200, Laurens Holst wrote:
>> No. In some situations you need to wait a long time (imagine the wait of
>> 2 NOPs on a 7Mhz cpu or on TR). We ALWAYS want speed but 100%
>> compatible.
>No. On EVERY 7MHz board the processor switches back to 3.5MHz when accessing
>the VDP. SO that's compatible.
You forgot that NOP is not an VDP Acess, so it will happen at 7Mhz in the time of 1
NOP
at 3.57Mhz.
> On the turboR, an auto-delay is inserted by
>the MSX Engine. So there even two OUT-instructions behind eachother works!!!
>The processor will automatically wait the nessacary time.
Nah, correct SOFTWARE problems using hardware is BAD.
>So inserting two EX (SP),HLs is just a big, unnessacary waste of time, as
>well on 3.5MHz, 7MHz and turboR MSX computers.
Ok. This type of programing give us A LOT of trouble correcting programs
and trying to find out 'why it's not working while all other programs work well?'
>> FAST almost always means incompatible.
>What should I use the BIOS for?
Acess VDP, there is problems and diferences of timing when using VDP1 or
VDP2 or VDP3, use the mouse. Use OPL driver to Acess FM (acessing it
directly causes almost all games have a BAD sound under 7Mhz), use
BDOS to acess disk (or you'll have problems with port based or memory
based interfaces (it will depends on how have you done the direct acess).
> The only incompatible thing for which I
>should actually use the BIOS is the mouse... but reading the mouse is a
>really speed-sensitive thing (readout is done every interrupt)... So I don't
>use that BIOS-routine.
Hehehe... Ok. That will be your problem if the program work only in your
hardware.
If you NOT use BIOS, you are NOT programming for MSX standard. You
are programming for a computer using, Z80, V99xx, PSG, YM2413, etc,etc,etc.,
on the same ports/addresses than a MSX.
Why? Because the standart says to use the BIOS... Even if it is slow. And
if someone do a NEW MSX and DO NOT reprogram the BIOS, than it will
not be a good MSX. There is the need of a new BIOS. And you'll see something
about it in the future.
>About other things... I only use the (Disk-)BIOS for disk I/O. The BIOS is
>really useless, the most needed BIOS function is not even available (only in
>MSXDOS2)... Can you guess what I'm talking about? Right! Memorymapper
>management routines!!!
(-: This is right... But this is THE ONLY thing I do not want to use, because the
DOS2 memory management is really weird.
>If they had included these... That would be another story.
Why not WE include?
>Please name some other thing which could be incompatible when not using the
>BIOS...
>- Mouse? Indeed a problem because of timing, but the BIOS routines are way
>too slow (I can program it at least 6 times faster). Aargh!
Yeah, but it will work everywhere? If it's 60 times faster but runs only on my
system, it's useless.
>- VDP? Timing is indeed quite strict, however the speed is much too
>nessacary to keep account with that. Therefor the faster MSX computers have
>adaptions to slow down VDP access.
Hehehe... Yes, a lot of waitstates... This is weird.
>- Disk? Is definately incompatible using direct I/O. Is too difficult to
>program though so everybody uses the (Disk-)BIOS anyways.
(-: This is the worst point of direct acess!
[]'s Daniel Caetano ([EMAIL PROTECTED])
...Have you crashed your Windows today?
OS/2 Sites: http://www.os2brasil.com.br/novidades/
http://www.os2brasil.com.br/novidades/drivers.shtml
http://www.geocities.com/SiliconValley/8752/os2hp/index.html
MSX Sites: http://www.fudeba.cjb.net/ e http://www.msxnews.cjb.net/
MSX Phoenix: http://www.msxphoenix.cjb.net/
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