Hi!
>
> thank you for replying my question about the 7MHz musicreplay. Some
> months ago I did some tests: I connected some internal 3.58MHz signal
> directly to the SCC and to the MSX-Audio. The SCC did work fine. But the
> Audio sometimes skipped a note like Laurens described. I thought this
> was due to the fact that the read/writecycles (@7MHz) to the audio were
> not synchronized to its clock (3.58MHz). Now I looked it up in the Y8950
> manual and there is nothing said about sync. between the
> read/writecycles and the clock. So the 'skips' are probably caused by
> the too fast I/O in the moonblaster replayerroutine (probably Laurens
> used this too).
> All this confirms wat Laurens has written.
No the problem actualy is in delay between outputs to the address
and data ports of Y8950. This chip needs a lot of delay -
just like old AdLib OPL chips did.
> 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')
>
> Officially there is the CLOCK signal (pin42) and it should be 3.58MHz.
> (Even on Turbo-R in R800 mode the CLOCK signal is 3.58MHz, can someone
> confirm this? What about the read/write cycles, are these at 3.58MHz
> too? then R800 has no use when programcode is running in an external
> mapper?!)
Well, I put 3.58 clock on the clock pin in the slot, and I have WAIT inserted
_after_ any I/O operation. MusicModule works fine at 10.5 MHZ in my
computer, as well as SCC. External mapper will not work in this
configuration, and IMHO external mapper on TurboR just works
slower than internal DRAM. That's probably the answer.
--
Signed: Egor G. Voznessenski
[MSX Maniac] [Pendorian wannabe] [Tubed audiophile]
http://www.glasnet.ru/~msxegor
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