Alwin Henseler wrote:
>
> Hi you all..!
>
> >
> > HARDWARE PROPOSAL:
> > ------------------
> > In stead of building an internal 3.58MHz clock in all SCC's, Audio's and
> > Musics it would be convenient to have a fixed 3.58MHz clocksignal
> > available on the cartridgeconnector and also a 'BUSCLOCK' which reflects
> > the processor's speed. My proposal is to use pin16 for this (currently
> > 'Reserved')
>
> The idea is excellent....I had it some 3 years ago, BUT:
>
> There's no way you can 'standardise' this somehow.
wrong. It is very unlikely that ASCII Corp. will continue the MSX
development. So the only persons who can optimize the MSX system are WE.
This mailinglist is an excellent instrument for doing this. Just look at
the JoyNet proposal. It is good for everyone that some (new) things are
standardized and agreed.
> No matter what
> reserved cartridge-pin you take, or what signals you put on them,
> you'll always have the same problem:
>
> You'll have to modify SOME cartridges to work in a modified machine,
> or some modified cartridges won't work in non-modified machines,
> and/or some non-modified cartridges won't work in modified machines.
>
> You might try and fix this for some of the most common cartridges,
> but this problem remains. And you will all know how many different
> hardware add-ons there are for MSX.
AFAIK the only cartridges that will need modification(one wire changed)
are the external memorymappers if you want to use them on a modified MSX
(or in other words on a 7MHz MSX)
> If you just supply a music
> cartridge with it's own independent clock source, you don't have
> these problems, but instead expanded the conditions such a cartridge
> can work with. Besides: a simple 3.58 MHz. oscillator might consist
> of a cheap IC, a few resistors & capacitors, and a crystal. Build it
> compact, and I couldn't think of any cartridge, where this wouldn't
> fit into. And it won't cost anyone serious money either.
I agree, but admit, it would be more convenient to have the fixed
3.58MHz signal on the cartridgeconnector: the advantages are major, like
you've said yourself:
> The idea is excellent....
No need to open your sounddevices if you want to be able to listen to
great music and see some fast (7Mhz) videoaction. And it only takes two
wires inside your 7MHz msx. And if you use an external mapper it only
needs one-wire-modification.
New memorymappers can have a jumper to choose between CLOCK(for
unmodified MSX'es) and BUSCLK(for new ones).
New slotexpanders can have a jumper too. Makes it easy to support old
mappers without jumper.
>
> Conclusion:
> ----------------
>
> Do this for yourself, for your computer(s) & your cartridges,
> fine, but I would not support any attempt to set some standard for
> these modifications. That would only be a source of problems for
> years to come....
I only can see the problems today: you can't enjoy your 7MHz expansion
because your music is screwed up.
>
> If you do, I suggest you make it switchable, such that in one state,
> it works like non-modified (like with turbo-circuits: switch it off,
> and it works like it wasn't there).
No need for that, because there is a 3.58MHz clock available at pin42
like the MSX standard requires.
>
> Putting a fixed frequency signal, and a variable CPU clock/bus speed
> signal, side by side on a cartridge-connector is a good thing, but
> for the MSX system, the chance to do so was lost with the definition
> of the MSX standard, no way to re-do this.
Not so negative! 'Reserved' signals are intended for future expansion!
Don't Fight the Future ;-)
I can't see any disadvantage of using one of these to supply a variable
busclock, useful for hardware who is supporting it.
BTW current 7MHz (and other 'turbo-things') are not compliant to the
MSXstandard because they alter the 3.58MHz CLOCK at pin42. Modify them
with a couple of wires and your soundproblems are gone without messing
around with your precious Audio, Music or SCC.
>
> Alwin Henseler ([EMAIL PROTECTED])
>
I really appreciated your reply and point-of-view,
Jon
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