Search found 26 matches

by BenOVR
Tue Jul 04, 2017 6:33 am
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

In summary, measures on a real YM shows that most documentation / emulation are wrong or incomplete ; period counts up from 0 to max_per, noise counter is incremented twice slower than tone counter and writing to envwave register does both a restart of the wave pattern and a new phase. The only thi...
by BenOVR
Sun Jun 11, 2017 3:54 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Nice work. Thank you.

With sc68 for a long time I've always reset the envelop counter at the same time the envelop shape was written without knowing if it was right or not.
by BenOVR
Fri May 26, 2017 3:45 am
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

My latest and more precise results with a long run of mfpcpu4.prg:

stfpal-zoom.png
Overview

stfpal-overall.png
Zoomed
by BenOVR
Wed May 24, 2017 9:03 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Just another unrelated thing I was thinking about: When writing the register #13 we know it resets the envelop shape. But does it reset the envelop period counter as well ? Hi I don't have my tests with me at the moment, IIRC it doesn't, but I will try to check this (using a rather low freq and wri...
by BenOVR
Wed May 24, 2017 7:33 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Just another unrelated thing I was thinking about:

When writing the register #13 we know it resets the envelop shape. But does it reset the envelop period counter as well ?
by BenOVR
Wed May 17, 2017 4:02 pm
Forum: Demos
Topic: "We Were @" music
Replies: 7
Views: 5315

Re: "We Were @" music

Ça va !

Zappy just asked the same question on facebook. It would be mice if you could find that in your archives. I thought of doing one a few time. I always stop at the lha part. I thought I had a lha depacker in asm written by M-coder but I lost it (or I'm remembering wrong).
by BenOVR
Wed May 17, 2017 1:48 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Thank you tin I would appreciate that. I have an updated version of the program that allow to change the SID parameters on the command line but I still have problems to communicate with my ST so it's not available at the moment. Meanwhile you can record my previous attachment . The idea is that the ...
by BenOVR
Mon May 15, 2017 11:35 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

cpuclock170515.png Here is what I have recorded so far using my mfpcpu4.prg program. I'd like to cross the result with the SID-like dephasing program. Currently I'm doing it just by listening to the sound but it would be much better with a good recording (high sampling rate). It requires fairly lon...
by BenOVR
Fri May 12, 2017 11:19 pm
Forum: Demos
Topic: "We Were @" music
Replies: 7
Views: 5315

Re: "We Were @" music

Hi Leonard

Would be great to have an sndh too.

Do you have a native player for .ym ?
by BenOVR
Fri May 12, 2017 12:15 am
Forum: 680x0
Topic: machine language code
Replies: 33
Views: 6599

Re: machine language code

As M68k memory order is big endian

Code: Select all

   dc.b $51,$C8,$FF,$F8
   dc.w $51C8,$FFF8
   dc.l $51C8FFF8

are exactly the same byte sequence in memory.
My disassembler splits the opcode to help understand how it's encoded.
by BenOVR
Thu May 11, 2017 12:21 pm
Forum: 680x0
Topic: machine language code
Replies: 33
Views: 6599

Re: machine language code

Basically you can use any assembler/disassembler to do it. Just transform the hexa data to a form your assembler understand. Assemble the thing. Then use the disassembler to get the assembler listing. For instance I used vasm to assemble to binary the hexa sequence after converting it to the proper ...
by BenOVR
Thu May 11, 2017 11:50 am
Forum: 680x0
Topic: machine language code
Replies: 33
Views: 6599

Re: machine language code

Start: bra.s L01000A ; 6008 ori.b #$0,d0 ; 0000-0000 lea $fffe(pc),a0 ; 41FA-FFF6 L01000A: move.l $4(a0),d1 ; 2228-0004 tst.b (a0) ; 4A10 beq.s L010066 ; 6754 cmp.l #$fffffff,d1 ; B2BC-0FFFFFFF bhi.s L01005A ; 6240 moveq #$3,d0 ; 7003 L01001C: lsl.l #1,d1 ; E389 lsr.b #1,d1 ; E209 bclr #$7,d1 ; 088...
by BenOVR
Mon May 08, 2017 12:57 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

I can not comment on hardware logic. My knowledge in electronic is minimal.
by BenOVR
Sun May 07, 2017 10:40 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Thank you for that. It's pretty much what I do with sc68. I've never doubted for the envelop as I said it's in the audible spectrum (4000hz for a triangle). Both perE==0 and perE==1 sound exactly the same. But as we already know that tone_per=0 is similar to tone_per=1 and that env_per=0 is similar ...
by BenOVR
Sun May 07, 2017 5:23 pm
Forum: Ym rockin'
Topic: Sync-buzzer technique
Replies: 15
Views: 5930

Re: Sync-buzzer technique

Half the level is -3db. In YM scale it's 2 levels so basically a normal buzz is at volume level 15 a half buzz is at volume level 13. Teddy bear story in short: Jess composed these modules for an Amiga game (Stywox) in 1993. The game was abandoned. In 2015 I remembered those were 3 channels so I dec...
by BenOVR
Sun May 07, 2017 4:19 pm
Forum: Ym rockin'
Topic: Sync-buzzer technique
Replies: 15
Views: 5930

Re: Sync-buzzer technique

That's because Hatari 2.0 is generating the soundwave at 44khz directly so it can't generated the 125khz signal. It's possible to trick it. I think that's what winjam does (or did a long time ago when I spoke to Tao). The devel version of Hatari however should fix that. sc68 does that properly. It's...
by BenOVR
Sun May 07, 2017 12:13 pm
Forum: Ym rockin'
Topic: Sync-buzzer technique
Replies: 15
Views: 5930

Re: Sync-buzzer technique

The null period in the tone register is used to reduce the amplitude of the signal by 2. It's a a pulse at 125khz on top of the envelop and the lowpass filter do the trick. It's used to have a pseudo volume control for the buzz instrument. Mostly used to give an attack to the instrument. Have a look...
by BenOVR
Sun May 07, 2017 11:22 am
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

That's also something I wondered : it's known that writing per=0 then per=xxx will "reset" the square wave and immediately starts a new phase. But 1 cycle at 250 KHz is 32 cpu cycles à 8 MHz. So, if we write per=0 then write per=500 less than 32 cpu cycles later, we could expect that per=...
by BenOVR
Sat May 06, 2017 10:35 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

That noise thing was something I did age ago. At the time I was positive about it. I'm going to look for musics. In the meantime my PC boot is back ! I've attached the cancel-out sndh and sources. Thanks, I just tested it with Hatari 2.0 and new sound emulation : - with Hatari 2.0, phases never can...
by BenOVR
Sat May 06, 2017 7:07 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Okay that the same documentation. I'm not sure it matters either. I was just wandering how values were picked. That noise thing was something I did age ago. At the time I was positive about it. I'm going to look for musics. In the meantime my PC boot is back ! I've attached the cancel-out sndh and s...
by BenOVR
Sat May 06, 2017 5:50 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

There is no doubt that env=0 is equ. to env=1. It's in the audible spectrum (8000hz for sawtooth / 4000hz for triangle). If it were different you would absolutly hear it. I don't hear a difference with Hatari's not yet released new sound, but I guess I would need to run the music several times befor...
by BenOVR
Sat May 06, 2017 11:27 am
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

About the phase cancel out here is another example for you. That one puzzled me a bit until I used the channel masking capability of sc68. With sc68 the effect is even worst as the simulation is cycle less both channels are exactly in sync. As sc68 is deterministic the chip state is always the same ...
by BenOVR
Fri May 05, 2017 11:35 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

Attached is an example of sound (sndh) that might differ a bit between different clocks. It might be unnoticeable but if you test it with sc68 you'll hear the difference. Hatari seems to have some problem (may be with the filtering) with this one. It happens when the timer is synced on the low state...
by BenOVR
Fri May 05, 2017 5:26 pm
Forum: Hatari
Topic: MFP / CPU clock ratio
Replies: 70
Views: 15536

Re: MFP / CPU clock ratio

The way the timers are used usually for sound FX don't really rely on such precision. I'm a bit too lazy to compute the drift but I'm willing to try to find the best matching frequency between the YM and the timer on a standard SID voice by ring modulation. That's the effect that is the more likely ...

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