> >Err... isn't two NOPs easier??? Or an LD A,value:OUT (#99),A (the LD
A,value
> >is 7 T-states)...
> >It is only nessacary to wait 7 Z80 T-states (So in reality 8 T-states on
> >MSX). LD A,value takes 7 T-states. If executing an IN right after an OUT
you
> >can best put an LD A,(DE) inbetween. It only takes 7(8) T-states (2xNOP
> >takes 8(10)), and it is only one byte (2xNOP is two bytes).
>
> 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. 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.
So inserting two EX (SP),HLs is just a big, unnessacary waste of time, as
well on 3.5MHz, 7MHz and turboR MSX computers.
> >> they ignore the BIOS...
> >I NEVER use the BIOS. It's just so da@# f&*$king SLOW!!!
>
> FAST almost always means incompatible.
What should I use the BIOS for? 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.
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!!!
If they had included these... That would be another story.
Please name some other thing which could be incompatible when not using the
BIOS...
- Printer? Not. Uses a speed-insensitive transfer protocol using strobe &
acknowledgement-signals etc.
- Slotswitching? Actually isn't incompatible to use direct I/O acces either.
- 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!
- Joystick? Consists just of a few simple switches, so no timing problems.
- 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.
- Disk? Is definately incompatible using direct I/O. Is too difficult to
program though so everybody uses the (Disk-)BIOS anyways.
~Grauw
--
>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<
email me: [EMAIL PROTECTED] or ICQ: 10196372
visit the Datax homepage at http://datax.cjb.net/
MSX fair Bussum / MSX Marathon homepage: http://msxfair.cjb.net/
>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<
****
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/)
****
