TM>Well, in ALL JCH tunes there are two $d418 "pokes", one is
in the init
 TM>routine, and one is at the end of the main player loop. If you hunt
 TM>through for "18 D4" you find both... the first one is the init one.
 TM>From memory, DMC 1.2 is very similiar, in fact, I'd say that it's
 TM>exactly the same (different memory locs though).
 TM>VoiceTracker might be a bit different, I'll check and get back to you.

 Yep, sounds right to me. If your digi player was -really-
intelligent, it could do a hunt through $1000-$2000 for $18 $d4, and use
what it found (-: (nah, too damn hard, you could only assume that the first
one found was the init.. (usually is)).
 Of course all this discussion is only of use if you are actually going to
write a digi-organiser type clone.. (-:

 TM>I'm thinking about it... at the moment though, I'm just trying to find
 TM>some time to relax (been a rather stressful few weeks)
 
 Well do it! After you've built a working version, I'll sponge the circuit
off you & build my own. (: How you can be stressed when you dont even
work is beyond me however.. (-: (depressed, even suicidal I could believe,
but stressed? when you have a continuous holiday? (: )

 TM>Hey, there's one important factor here... I'm not TBH! ;) And Moonlight
 TM>is definately not "nearly finished" either.
 
 What? Aren't you?? Damn! & I though you were one & the same! (-:

 TM>Hmm, JCH's, DMC and Voicetracker can all do this... it's just not used
 TM>that much.

 Yeah, I figured that.. Although I think the music I am thinking of
probably changes waveforms & possibly frequency slightly as well.

 TM>Is there a way to control the volume of a sample? What happens if you
 TM>chop the top two bits (or so) off the top of a sample? Also, what would
 
 Volume? Several possible ways, all with disadvantages. On newer 64's &
128's, the signal has to be 'carried' on a 100% pulse width square wave (ie
a DC level). You could change the sustain level of the 'carrier' voice to
change the apparent volume. Wont work on old 64s tho!
 Probably the easiest way would be to use several 16 byte tables for volume
control, and instead of just:

STA $D418

 you would have something like:

TAX
LDA volumetable,X
STA $D418

 And you would change which table you loaded from, and the tables would
have different 'scales' of volume from 0-15. I think I
explained that alright.. (-: ie a 'full volume' table would go from 0-15,
but a 'half volume' table would have 16 values from 0-8. So a $0f in the
sample would actually only put a $08 in the volume register.
 Actually, I've confused myself (: It's not that simple, as values actually
range from 0 to 15, 'centred' at about 8. So half volume would actually go
from 4-12..

 
 TM>chop the top two bits (or so) off the top of a sample? Also, what would
 TM>happen if you got an eight bit sample, and played the high nybble on
 TM>one SID, and the low nybble on another SID? Would that constitute eight
 TM>bit sound? There is a new program coming out that has full eight bit
 TM>sampling on the 64... commercial though :( I might buy it anyway, as it
 TM>has some info on connecting an Amiga sampler to the 64... speaking of
 
 As I just attempted to explain, the samples are centred at 8, so chopping
off the top couple of bits would wreck the sound, ie no you cant do it that
way! (I wish you could). Also, LSR'ing wouldnt work (pity)..
 As for 8 bits, it would only work on 2 SID's if you could play the lower
nibble sid at exactly 1/16th the volume of the high nybble sid, which is of
course impossible! The only way to play samples >4 bits on a 64 is to
use PWM, which gives you up to 12bits in theory, but the quality sux (:
 btw, Datel's sampler could record & play back at 8 bits, so this
commercial product you have found is not original. My home made sampler
(hacked amiga design) is actually 8 bit, & I just LSR LSR LSR LSR the
sample to get 4 bits out of it. (I'm lazy & couldnt be bothered just
rewiring it (-: )

 TM>which, do you think you could tell me why all I get from my sample is a
 TM>VERY distorted of what I'm playing through it? Yes, I was trying to
 TM>modify the volume nobs and the imput level, but even if the level was
 TM>at .001 of the volume it still distorted majorly. And turning it up
 TM>seemed to make no difference (except that it cuts out sometimes).
 
 Sounds like you have the signal wires mixed up. I think you told me that
you had just connected the high 4 lines from the sampler to the lower 4
bits of the user port. It is possible that a) you got it mixed up &
have connected the lower 4 bits from the sampler, or b) you have the wires
back-to-front (ie bit 0 connected to bit 3 etc).
 Or even a combination of the above! (: The ADC0802 chip has the pinouts as
bit 7 is pin 11, bit 0 is pin 18. The ADC0804 in your amiga sampler has the
same pinouts. (to my knowledge). Check to make sure you have it the right
way round. Try connecting all 8 lines like I have if you are still not sure
what is wrong.
 btw with nothing connected to the sampler, it should read about 127-128
(or 7-8 in your case) on the user port. There -may- be an adjustment ont he
sampler to 'centre' it. Some samplers are fixed though, and the knob only
adjusts volume..

 TM>How about a "blitter" effect, ie: turning the sample on
and off, while
 TM>still updating the sample pointer...
 
 Yeah, I can think of an easy way to do that actually, instead of AND #$0F,
just self-modify it to AND #$00 (-: Well that's 3 effects, keep em coming!
(-: btw with the 'looping', I can get the loop start to within a byte, but
the end of the loop must be on a page boundary. (the code would just be TOO
long if I had to check if it ended every time I incremented the sample
address..)

 TM>Perhaps you could write an article for them about sampling? With demo
 TM>programs and so-on. I'm sure "duck" would be pleased!

 Haha, I might (: There is a bit of discussion in comp.sys.cbm on sampling
at the moment, with some people giving long descriptions of how NMI's work
etc. (often incorrectly unfortunately).

btw, I got hacking #1 from his mailserver (if you want it).

later, Strobe/Menace

btw2, working on a basic pattern/track player for digis at the moment,
should have something working by tonight..

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