I'm quite busy with other things like msxdev atm so I haven't been doing anything. I looked at your last samples and they look ok but I didn't do much analysis on them. I think it would be good to verify that the phase is ok and that the amplitude of the sum of the for channels is correct. It sounds like either of these two aren't correct for some reason. I hope its not a hardware bug/feature and that its something we can improve in software.

Hi Daniel,

long time has passed since you started this thread.

With the release of Montana John and the Templar's
Treasure many developers have found problems in
the SCC.

From what I see here:

http://www.msx.org/forumtopic8299p15.html

It seems that SCC+ has less design flaws.

I think that it is time to rethink to the PCM player using SCC+.

If all the HW problems of SCC have been solved
by KONAMI with the introduction of SCC+, we can just
keep the current strategy of multiple offsets and use
that chip.

Moreover using the 5 waveforms of SCC+ would allow an higher
frequency of replay.

Exactly 8 KHz when in PAL mode and 9,6 KHz when in NTSC mode.

What you think of this ?

PS
Could you test the latest player for SCC on a SCC+ in compatibly mode ?
If the noise disappear this means without doubt that this latter chip has
no bugs.

Yes I've been following these threads too and basically they found a technical reason for the problems we already identified. Its kindof unfortunate that it is a hardware problem. I was hoping there was some issue with our implementation. Ah well...

I was btw, thinking of going the other way and doing a 3 channel PCM instead of 4. The main reason is that from what I heard its hard to find those SCC-I chips so I'm not sure how easy it will be to produce actual cartridges with that algorithm.

Unfortunately I don't have an SCC-I to do any testing with but it should be quite easy to update the code to do 5 channels instead of 4. Do you have one of those SCC-I chips?

Humm, why using 3 channels would improve the quality of the output ?

Unfortunately, now I have 2 SCC roms,
but I do not have any SCC+ cartrige,
sorry.

Maybe someone on MRC could tell us if SCC+ has solved the HW flaws in the
SCC, and if it is worth to approach the 5 channel PCM player.

You could do a version of the current 4 channel player able to be loaded in the
64Kram that comes with the SD cartridge that has the SCC+.
Just a matter of adding a loader, no need of switching on fly the slots.

If volunteers report no noise in the output, it would be nice to develop an scc+
replayer at 9,6 KHz,

I have an scc+ because i have the original Snatcher from konami that ships with such a card.Scc+ card works perfectly tell me what do i need to test with such a card.

Thanks!! If dvick resurrect the project, your support could become precious.

PS
from here http://bifi.msxnet.org/msxnet/tech/pinouts.txt
I see that:

Quote:

- The sound chip has a 11 bits digital output, which is converted to analog by an array of resistors.

so in SCC channels are mixed digitally.

Is here the flaw accordingly Edwin's guess?

Actually, the resistor array might explain how it sounds different on other chips.

Apart from that, it's difficult to say. 11 bits suggests addition of 5 8bit values. But before that, wave data is multiplied with the volume, which is essentially a row of adders as well.

Also a note about using two SCCs. While channel 4&5 are by far the worst, I'm not entirely sure the rest is completely clean.

hi nikodr
send me an email, if you are available to test some code on your scc+

Quote:

Also a note about using two SCCs. While channel 4&5 are by far the worst, I'm not entirely sure the rest is completely clean.

I think its at least much cleaner. You can try the Leila K demo

Its playing an 8 bit sample on SCC channel 1. I did need to do some tricks though. This is the algorithm in the replayer:

LOOP:
1. Load first 16 samples in the SCC sample RAM (should be done while the SCC is playing sample 28-31 close to wrap)
2. Set the SCC period to the sample period forcing the replayer to start from sample 0.
3. Load second 16 samples
4. Delay enough so that this loop is as close to a full SCC period as possible without wrapping)
5. Goto LOOP

This was the closest I got to a clean SCC sample player. I really haven't had time for any MSX activities last week and will probably be too busy next month or so but when I have time I'd like to see if the replayer we talked about in this thread could work on SCC-I or the standard SCC with channels 1-3 only.

Quote:

hi nikodr send me an email, if you are available to test some code on your scc+

I am available!Just sent you an email.Dont know if you received it!

My email is MPERDEMAS at YAHOO dot GR

At your service for any test needed for your pcm player.

Hi, thanks! I've got your email
I'll send you something asap, unfortunately,
I tested the code I wanted to send you
on the emulator and strangely it hangs,
so i need a bit more time before asking you to test.

BTW I found a SD scc-I cartridge here:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=320239444330&ssPageName=ADME:B:SSG:US:1123

Is price too expensive ?

Quote:

Is price too expensive ?

Not really; but it will end a bit higher than this for sure...

nikodr
have you never tried to use
http://bifi.msxnet.org/msxnet/tech/scrom.zip
to load some standard SCC rom?
what you get running e.g. Leila K demo ?

Even if it does not fits in the ram, it should
work giving at least some seconds of valid
output.

have you tried if that sound is clean ?
Strangely on bluemsx, if you load with scrom into the scc+ cartridge
any scc rom of this tread, including leila K
the sound is absolutely crappy (!?!)