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2016-11-05 18:28

Steppe

Registered: Jan 2002
Posts: 1510

Release id #151275 : Wonderland XIII

In the production notes Bob writes:

"There is an hidden feature in the demo to determine the sample playback quality on your SID chip. Hold down fire on joystick in port two while the demo is starting and you will get a border color. The color means:

Green = Best (8580)
Yellow = Good (8580)
Red = Bad (8580)
Gray = Unknown (8580)
Dark gray = Bad (6581)
Black = Awful (6581)"

I'm using Sidfx with a 6581 and 8580 and no matter which model I select, I always get the "black / awful" screen and this shows in the sound quality, really noisy...

To double check, I tried the demo on my C128D-CR (metal case with 8580) and I get a yellow border and the sound quality is really a lot better, a whole different league! Cheers for making the demo work on my old metal 128!

Bob, can you explain that border coulor check? What does it do and why doesn't it work properly with the Sidfx?

2016-11-05 18:30

Steppe

Registered: Jan 2002
Posts: 1510

Is it related to the Sidfx at all? Can some of you Sidfx users try this on your machines?

2016-11-05 22:21

CreaMD

Registered: Dec 2001
Posts: 3057

Steppe try on plain C64 before you ask... ;-)

2016-11-06 07:46

Steppe

Registered: Jan 2002
Posts: 1510

Roman, you probably misunderstood. I'm not saying there's something wrong with WL13, but it's the hardware extension Sidfx that's causing unwanted trouble. Of course I'm using it in a real C64 and also compared the strange result with an "untouched" machine, my 128D.

The Sidfx guys meanwhile cleared it up a bit. A SID detection routine will always detect the SID in socket 1, no matter which position the SID select switch is in. So I swapped the SIDs (#1: 8580 and #2 6581R3) and I'm now getting a light gray border with brutally improved sound quality in the end part. So you can consider the riddle solved.

Still, would be nice to know some technical stuff behind these various quality levels that are possible, depending on the chip type and probably other frame conditions. I mean, an 8580 is an 8580, but there are three (four) levels of quality possible. What is it that gives me green, yellow, red, or in my case, gray?

2016-11-06 08:53

Swallow

Registered: Aug 2013
Posts: 5

The routine first does a model detection and then checks the ability to use combined waveforms for sample playback on your chip.

It is interesting that you get an unknown configuration. Do you have the ability to test another detection routine if I send one to you?

2016-11-06 13:55

Steppe

Registered: Jan 2002
Posts: 1510

Sure, always happy to help out Swallow.

2016-11-06 14:37

Frantic

Registered: Mar 2003
Posts: 1648

Quote:

Still, would be nice to know some technical stuff behind these various quality levels that are possible, depending on the chip type and probably other frame conditions. I mean, an 8580 is an 8580, but there are three (four) levels of quality possible. What is it that gives me green, yellow, red, or in my case, gray?

Yes, this made me curious as well. Swallow? Different 8580 chips play combined waveforms in different ways, or what?

2016-11-06 17:20

Swallow

Registered: Aug 2013
Posts: 5

The routine uses different combined waveforms, eg. combinations of pulse, sawtooth and triangle, to play the sample. The SID spec states that if more than one waveform is selected, the output will be an logical and between the selected waveforms but this is not true. Different chips generate different output when combining waveforms, even chips with the same model. The resolution of the samples depend on how many combined waveforms that produce useful output on your chip.

2016-11-06 17:40

Frantic

Registered: Mar 2003
Posts: 1648

Quote: