analmux Posted January 31, 2004 Share Posted January 31, 2004 I've been experimenting with timer irqs, and this is the result: When we use channel 2 for both timer irq and sound at once, and we use the interrupt to write alternating pitches to audf of channel two, we can make asymmetric squarewaves, like the picture titled wave below, the picture is a recorded pokey sound. Now we're able to make more NES-alike sounds, we have a variable pulsewidth now (like a c64). The principle: When pokey makes a sound it resets a counter and every 1/63921th of a second it's incremented untill the value 'f' stored in AUDF is reached, so it waits (f+1)*(1/63921) seconds when the Pokey-basefrequency is 63921 Hz. After counting, the wave goes from up to down, or from down to up. This means that we have a frequency: Pitch = 63921/(2*(f+1)) because in one period of the waveform a squarewave has an up and a down side. Pokey generates 2 irq's per period, one at the transition from up to down, and one at the transition from down to up. When we define f1 and f2 in such a way that f1+f2 = 2*f and we do this: (*) At the first (even) IRQ we write f1 to AUDF (*) At the second (odd) IRQ we write f2 to AUDF we can change the timbre to an asymmetric waveform with an excentricity epsilon. I've written down how to compute f1 and f2, with given f and epsilon, in the picture labeled equation Quote Link to comment Share on other sites More sharing options...
analmux Posted January 31, 2004 Author Share Posted January 31, 2004 I also wrote a demo (to be runned on real machine). Sourcecode included Just bootup main.atr and plug in joystick in port 0. Push trigger to start a sound. The program starts at f = 72, f1=f2=f. With left/right you can change the excentricity With up/down you can change the pitch. Watch the grey bands on screen to see how the pulses evolve. Quote Link to comment Share on other sites More sharing options...
analmux Posted January 31, 2004 Author Share Posted January 31, 2004 This is the sourcecode: ; Pokey demo 1 for atari xl/xe series ; 'variable pulsewidth' ; january 31 2004 ; by Analmux ; written for xasm trig0 equ $d010 colbk equ $d01a audf0 equ $d200 audc0 equ $d201 audf1 equ $d202 audc1 equ $d203 audf2 equ $d204 audc2 equ $d205 audf3 equ $d206 audc3 equ $d207 audctl equ $d208 stimer equ $d209 irqen equ $d20e skctl equ $d20f porta equ $d300 portb equ $d301 nmien equ $d40e nmist equ $d40f z_f equ $80 z_f1 equ $81 z_f2 equ $82 z_endflag equ $83 z_flag1 equ $84 z_flag2 equ $85 z_phx equ $86 z_joy equ $87 stack equ $0100 dliv equ $0200 vbiv equ $0222 org $2000 start jsr init st_0 lda trig0 bne st_0 jsr start_sound st_l lda z_endflag beq st_l jmp st_0 init lda #0 sta nmien ldx #8 ip_0 sta audf0,x dex bpl ip_0 lda #72 sta z_f sta z_f1 sta z_f2 mva #3 skctl sei mva #$fe portb mwa #nmi_handler $fffa mwa #irq_handler $fffe mwa #vbi vbiv cli rts start_sound mva #0 irqen sta z_endflag sta z_flag1 sta z_flag2 mva #2 irqen ;enable audf1 timer irq sta stimer ;start timer mva z_f audf1 mva #$a8 audc1 cli mva #64 nmien rts irq_handler pha lda irqen and #2 beq ih_0 pla:rti ih_0 mva #253 irqen mva #2 irqen lda z_flag2 eor #1 sta z_flag2 tax lda z_f1,x sta audf1 lda z_flag1 eor #8 sta z_flag1 sta colbk lda trig0 beq ih_1 inc z_endflag stx z_phx tsx inx inx lda stack,x ora #4 sta stack,x ldx z_phx mva #0 audc1 sta colbk sta nmien ih_1 pla rti nmi_handler bit nmist bpl vbi vbi cld pha txa:pha tya:pha mva porta z_joy lsr z_joy bcs vb_0 jmp joy_up vb_0 lsr z_joy bcs vb_1 jmp joy_down vb_1 lsr z_joy bcs vb_2 jmp joy_left vb_2 lsr z_joy bcs evbi jmp joy_right evbi pla:tay pla:tax pla:rti joy_up lda z_f cmp #10 beq ju_x dec z_f lda z_f sta z_f1 sta z_f2 ju_x jmp evbi joy_down lda z_f cmp #255 beq jd_x inc z_f lda z_f sta z_f1 sta z_f2 jd_x jmp evbi joy_left lda z_f1 cmp #10 beq jl_x lda z_f2 cmp #255 beq jl_x dec z_f1 inc z_f2 jl_x jmp evbi joy_right lda z_f1 cmp #255 beq jr_x lda z_f2 cmp #10 beq jr_x inc z_f1 dec z_f2 jr_x jmp evbi org $2e0 dta a(start) Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted February 1, 2004 Share Posted February 1, 2004 raster must be interested in this kind of stuff... i don't understand 1% of that! very cool... i'll have to check it on real machine tonight... (TMR i hadn't the chance to play around with CC for the review i promissed.... but will do today) sometimes i wish god had gave me a more math & physic experience but i am a pure marketing guy with some programming experience... ps. wavelab is one of the ugliest software around but very powerful... hahahha... Quote Link to comment Share on other sites More sharing options...
miker Posted February 1, 2004 Share Posted February 1, 2004 Sound good! Like i though you`ve used 2 channel to do this - but the result is cool! Hve: there were rumours of discountinuing the RMT project, due to `coming soon` new version of Jaskier`s TMC - i wish that they were only rumours... Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted February 1, 2004 Share Posted February 1, 2004 but will jaskier make a PC TMC 2.0 or will it be again a atari8bit version only? i would prefer PC tool... just because more comfortable... Quote Link to comment Share on other sites More sharing options...
Jaskier Posted February 1, 2004 Share Posted February 1, 2004 raster must be interested in this kind of stuff... i don't understand 1% of that! I'm understanding 100% The only thing I'm thinkink is: it is possible to play 2 differents sounds on one channel? If yes, there is the possibility to play stereo music on one pokey Unfortunatelly pokey generates irq only for 3 channels P.S. TMC 2.0 will be of course Atari executable. Quote Link to comment Share on other sites More sharing options...
Schmutzpuppe Posted February 1, 2004 Share Posted February 1, 2004 I allways wonder why Pokey timers are one of the most unattended features of the A8. It's a mighty feature and to use it for sound generation could enhance the complexity and quality of sound a lot. I will check out your prog. today mux, I am curious about the result. Quote Link to comment Share on other sites More sharing options...
miker Posted February 1, 2004 Share Posted February 1, 2004 but will jaskier make a PC TMC 2.0 or will it be again a atari8bit version only? i would prefer PC tool... just because more comfortable... I don`t think if Jaskier will make PC version of it - it`s rather dedicated to people using the REAL stuff. So Raster can continue his project without any worrings, i think. Quote Link to comment Share on other sites More sharing options...
Captain Harlock Posted February 1, 2004 Share Posted February 1, 2004 Off Topic: If you want to avoid the numbering of the formulae in LaTeX, simply append an asterisk to the eqnarray. You write: begin{eqnarray*} Your equations end{eqnarray*} Quote Link to comment Share on other sites More sharing options...
analmux Posted February 1, 2004 Author Share Posted February 1, 2004 Off Topic: If you want to avoid the numbering of the formulae in LaTeX, simply append an asterisk to the eqnarray. You write: begin{eqnarray*} Your equations end{eqnarray*} Yes thanks, but the numbering didn't bother me. ----- Well, for those who do not understand the principle completely (Heaven): The excentricity 'e' is always a value between 0 and 1. when e=0 we have f1=f2=f and the wave will be perfectly symmetric. f1 is the pulsewidth of the upper part of the wave f2 is the pulsewidth of the lower part of the wave so when f1=f2 we have the original squarewave. when e=0.99999 we have f1=0.99999*f and f2=0.00001*f and we have a very small peak instead. when e=1 we don't have a wave at all. Now we can solve some tuning problems too. When we want a note between f=34 and f=35 (that is: 34.5) we define f1=34 and f2=35 then the effective pulsewidth is f=(f1+f2)/2=34.5 and the excentricity is minimal, so we have a true pitch of 34.5 and an almost symmetric squarewave. To answer another question: it is possible to play 2 differents sounds on one channel? If yes, there is the possibility to play stereo music on one pokey hmmm, could be, but you must expect more distortion, as it's not possible to play clear waves (without a lot more cpu investment) Maybe when we have a four-step alternating pitch instead of two-step, then maybe we can (even two assymetric waves). I must experiment with it at once. Quote Link to comment Share on other sites More sharing options...
emkay Posted February 1, 2004 Share Posted February 1, 2004 To answer another question:it is possible to play 2 differents sounds on one channel? If yes, there is the possibility to play stereo music on one pokey hmmm, could be, but you must expect more distortion, as it's not possible to play clear waves (without a lot more cpu investment) Maybe when we have a four-step alternating pitch instead of two-step, then maybe we can (even two assymetric waves). I must experiment with it at once. It shurely will not be possible to play stereo via one pokey because all channels are hard-wired in the chip itself. ... How much CPU does this cost ? Will it be possible anyway to combine those techniques with G2F ... I believe not. Quote Link to comment Share on other sites More sharing options...
Jaskier Posted February 1, 2004 Share Posted February 1, 2004 It shurely will not be possible to play stereo via one pokey because all channels are hard-wired in the chip itself. OK I say it wrong. I mean to play 8 channel (2 pokeys) music on only one pokey. How much CPU does this cost ? Will it be possible anyway to combine those techniques with G2F ... I believe not. Surely not. You cannot combine IRQ and DLI in one time. Anyway I must say that You probably can't use this technique on more than one channel. When there are 2 sources of IRQ the second must wait till finish of first IRQ procedure. It affects the sound for sure. But on only one channel with DLI turned off (and better also all screen) ? Maybe yes. I must try it when I get my machine back (it is in stereo upgrade now). Quote Link to comment Share on other sites More sharing options...
analmux Posted February 1, 2004 Author Share Posted February 1, 2004 It shurely will not be possible to play stereo via one pokey because all channels are hard-wired in the chip itself. ... How much CPU does this cost ? Will it be possible anyway to combine those techniques with G2F ... I believe not. I fail to understand your arguments. Pokey has only a MONO audio output, so you'd really need 2 of them to have stereo. This technique is hard to combine with G2F and especially GED, however MCS (with eventually a minimum of DLIs) is still possible. Playing two sounds via one channel is very tricky, I've tried to write a 4 step pulse. You can download it in pokeydemo2 below. You don't hear two notes. reason: I've defined f1, f2, f3, f4 for the 4 pulsewidths of the four steps. now h=f1+f2+f3+f4 is held constand (when changing excentricity of wave 1 and wave 2). So the resulting wave is h-periodical. But a two-note wave is Never h-periodical, but something else, I'll explain later. Instructions for the demo: when booting: if you hold down Start (while loading the prog, and not while the OS checks for a Tape-boot) before the loading ends the Audctl register is changed from 0 to 1 to change the pokey-basefrequency from 64 khz to 15 khz. It sounds constantly: joy up/down: change pitch (wave 1) joy left/right: change excentricity (wave 1) joy up/down + trigger: change pitch (wave 2) joy left/right + trigger: change excentricity (wave 2) Fun: when you choose 15khz basefreq. you can set the grey flickering bands still, and you can see clearly how the timing of the 4 step pulse alters when only changing excentricity of wave 1 and 2. Quote Link to comment Share on other sites More sharing options...
analmux Posted February 1, 2004 Author Share Posted February 1, 2004 It's best to use this technique only on one channel, but I don't think that multiple channel IRQ's are a problem as the changing of AUDF is not very timing-critical, as it's only checked by pokey at the end of a counting loop, the only thing that's important is THAT the audf is changed at an average timing. You also won't have to switch off the screen. It's nothing like playing digital sound, you may call it PSEUDO-SAMPLING, as with the avarage pitch = 72 we only have 880 updatings per second = 17 updates per frame. No problem. Now, this is the sourcecode for the second demo (4 step): ; Pokey demo 1.2 for atari xl/xe series ; polyphonic 'variable pulsewidth' ; 4 step alternating pulsewidth ; february 1 2004 ; by Analmux ; written for xasm trig0 equ $d010 colbk equ $d01a consol equ $d01f audf0 equ $d200 audc0 equ $d201 audf1 equ $d202 audc1 equ $d203 audf2 equ $d204 audc2 equ $d205 audf3 equ $d206 audc3 equ $d207 audctl equ $d208 stimer equ $d209 irqen equ $d20e skctl equ $d20f porta equ $d300 portb equ $d301 nmien equ $d40e nmist equ $d40f z_f equ $80;base PW (Pulse Width) of first note z_g equ $82;base PW of second note z_f1 equ $88;upper side PW of first note z_f2 equ $89;lower side PW of first note z_g1 equ $8a;upper side PW of second note z_g2 equ $8b;lower side PW of second note z_endflag equ $90;note sustain z_flag1 equ $91;colbk grey/black toggle flag z_flag2 equ $92;(0-3) PW index z_phx equ $93;temp x save register z_joy equ $94;joystick shift register stack equ $0100 org $2000 start jsr init jsr start_sound loop0 jmp loop0 init lda #0 sta nmien ldx #8 ;reset pokey sound ip_0 sta audf0,x dex bpl ip_0 lda consol and #1 eor #1 sta audctl lda #72 sta z_f sta z_f1 sta z_f2 sta z_g sta z_g1 sta z_g2 mva #3 skctl ;enable sound sei mva #$fe portb ;changing interrupt vectors mwa #nmi_handler $fffa mwa #irq_handler $fffe cli rts start_sound mva #0 irqen sta z_endflag sta z_flag1 sta z_flag2 mva #2 irqen ;enable audf1 timer irq sta stimer ;start timer mva z_f audf1 ;set default pitch mva #$a8 audc1 ;set generator a, volume 8 cli ;enable irq mva #64 nmien ;enable vbi rts irq_handler pha lda irqen and #2 beq ih_0 pla:rti ih_0 mva #253 irqen ;clearing IRQ flags mva #2 irqen ;re-enabling timer IRQ ldx z_flag2 lda z_f1,x sta audf1 inx txa and #3 sta z_flag2 lda z_flag1 eor #8 sta z_flag1 sta colbk lda #0 beq ih_1 inc z_endflag stx z_phx tsx ;finding stack offset of last pushed byte inx inx lda stack,x ;disable IRQs (sei) when returned from IRQ :) ora #4 ;bit 2 of pushed status reg = interrupt disable flag sta stack,x ldx z_phx mva #0 audc1 sta colbk sta nmien ih_1 pla rti nmi_handler bit nmist bpl vbi rti vbi cld pha txa:pha tya:pha lda trig0 ;computing offset, dependent of trigger eor #1 asl @ tax mva porta z_joy lsr z_joy bcs vb_0 jmp joy_up vb_0 lsr z_joy bcs vb_1 jmp joy_down vb_1 lsr z_joy bcs vb_2 jmp joy_left vb_2 lsr z_joy bcs evbi jmp joy_right evbi pla:tay pla:tax pla:rti joy_up lda z_f,x cmp #10 beq ju_x dec z_f,x lda z_f,x sta z_f1,x sta z_f2,x ju_x jmp evbi joy_down lda z_f,x cmp #255 beq jd_x inc z_f,x lda z_f,x sta z_f1,x sta z_f2,x jd_x jmp evbi joy_left lda z_f1,x cmp #10 beq jl_x lda z_f2,x cmp #255 beq jl_x dec z_f1,x inc z_f2,x jl_x jmp evbi joy_right lda z_f1,x cmp #255 beq jr_x lda z_f2,x cmp #10 beq jr_x inc z_f1,x dec z_f2,x jr_x jmp evbi org $2e0 dta a(start) Quote Link to comment Share on other sites More sharing options...
analmux Posted February 1, 2004 Author Share Posted February 1, 2004 And another picture to make clear the idea of the 4 step pulse: Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted February 1, 2004 Share Posted February 1, 2004 sounds like a racing game... you could even sell that "game" burnt onto cart... called "maniac bars"... in this exciting new game you task is to control the evil bars and controll them in the magnetic field not to move up and down anymore... hahahaha:) analmux...great work... and interesting to read.... Quote Link to comment Share on other sites More sharing options...
analmux Posted February 1, 2004 Author Share Posted February 1, 2004 Yeah...I even think it could be a 256byte game or something. I've got both Atari800win2.6 and the newest version (3.3 or so). On both emus the demo doesn't work properly, so be sure to run it on a real machine. Quote Link to comment Share on other sites More sharing options...
Jaskier Posted February 1, 2004 Share Posted February 1, 2004 I've got both Atari800win2.6 and the newest version (3.3 or so). On both emus the demo doesn't work properly, so be sure to run it on a real machine. Have you tried Atari800win PLus 4.0beta2 ? As I said before I don't have real machine for now so I cannot say that it is working but definitely something is going on. Something expected I would say. Atari800win PLus 4.0 has rewritten sound engine. Quote Link to comment Share on other sites More sharing options...
analmux Posted February 2, 2004 Author Share Posted February 2, 2004 Have you tried Atari800win PLus 4.0beta2 ?As I said before I don't have real machine for now so I cannot say that it is working but definitely something is going on. Something expected I would say. Atari800win PLus 4.0 has rewritten sound engine. I've checked the version number. It is 4.0.beta2 that I have. The effect in emulator is almost the same as on the real hardware, but the emulator skips every odd frame, and I can't adjust it. Quote Link to comment Share on other sites More sharing options...
analmux Posted February 2, 2004 Author Share Posted February 2, 2004 Sound good! Like i though you`ve used 2 channel to do this - but the result is cool! Hve: there were rumours of discountinuing the RMT project, due to `coming soon` new version of Jaskier`s TMC - i wish that they were only rumours... You've got it wrong. It's only ONE channel. The IRQ is generated by channel 2 (audf1), AND the sound is generated by channel 2 too. Not like sampling in which you use a 16bit channel to trigger IRQs at 22.050 kHz, and playing volume-only via another channel (though even the same channel could be used). ----------- It would be cool to see this technique applied in RMT and TMC. I don't know if I just re-invented the wheel now, but we can make a new standard sound-generating-technique out of this. Quote Link to comment Share on other sites More sharing options...
Jaskier Posted February 2, 2004 Share Posted February 2, 2004 The effect in emulator is almost the same as on the real hardware, but the emulator skips every odd frame, and I can't adjust it. You mean that the display is refreshed at 25Hz? It affects sound? Question to the stereo makers. It is possible to generate IRQ by the second pokey or only by the first? Quote Link to comment Share on other sites More sharing options...
analmux Posted February 2, 2004 Author Share Posted February 2, 2004 The effect in emulator is almost the same as on the real hardware, but the emulator skips every odd frame, and I can't adjust it. You mean that the display is refreshed at 25Hz? It affects sound? Question to the stereo makers. It is possible to generate IRQ by the second pokey or only by the first? Display seems to be refreshed at 50 hz, but the program seems to freeze every odd frame, that is: screen is just normal, without grey bands, and no sound. ------------ If the IRQ line of the 2nd pokey is connected, then it can generate IRQ too, otherwise you'd need to solder an extra wire inside the computer: not a very difficult job. @ Jaskier: By the way, how many DLIs does TMC use?? On what places are they, and is the used DLI code long or short? Maybe there is a way to combine DLI with IRQ simply by disabling interrupts ("SEI"), when DLI is runned, then after the DLI turn them on again ("CLI"). The IRQ flags will stay set until cleared, and a little retardation is not a real problem. Quote Link to comment Share on other sites More sharing options...
Jaskier Posted February 2, 2004 Share Posted February 2, 2004 Display seems to be refreshed at 50 hz, but the program seems to freeze every odd frame, that is: screen is just normal, without grey bands, and no sound. Not on my emulator If the IRQ line of the 2nd pokey is connected, then it can generate IRQ too, otherwise you'd need to solder an extra wire inside the computer: not a very difficult job. I've asked my stereo maker. He is doing stereo without irq connected. He will have to make some changes By the way, how many DLIs does TMC use?? On what places are they, and is the used DLI code long or short? Maybe there is a way to combine DLI with IRQ simply by disabling interrupts ("SEI"), when DLI is runned, then after the DLI turn them on again ("CLI"). The IRQ flags will stay set until cleared, and a little retardation is not a real problem. TMC 1.11 use about 10 DLIs to make screen so beautiful TMC 2.0 has DLI every text line due to special text mode (8x6 points , 39 lines of text.) On some dli-s the player is run so it takes up to 5000 cycles (during that some other dlis are run). I can enable irq during dli to allow sound change, but the real problem is the dli start. I've observed several times that irq is able to BLOCK dli and the particular dli is NOT EVEN RUN!!! So I'm sure that I cannot mix DLI and IRQ. The workaround for that is to disable IRQ and observe the IRQST ($D20E) in loop. When the irq should happen (but is not due to SEI) the bit in IRQST is cleared and then you can start your own irq routine (Yes, disabling irq in CPU doesn't disables irq in all atari so you can check when the irq should happen and start the apropriate routine, funny isn't it?) I've used this techinque several times for example in TMC when I read the pressed key. But when the music is playing I cannot check the IRQST register. The player routine is so long and I can miss several irq. P.S. I have to freeze developing TMC 2.0 for a few days. The polish translation of new Harry Potter has been just released Sorry Quote Link to comment Share on other sites More sharing options...
samurai Posted February 2, 2004 Share Posted February 2, 2004 we should burn some books nowadays... Quote Link to comment Share on other sites More sharing options...
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