andym00

I'm looking at finding some time to get into some Jaguar programming, but I'm a bit confused with the options available.. Are there any ~2MB (preferably 4MB) flash carts available that have USB or other high speed links, or am I looking at building one myself ? I see constant reference to some Jag CF cart, but can't actually find anything solid about this device.. Do you absolutely need a development Jaguar to use one of the Alpine boards ? Just curious about this, but in reality I don't really want to fork out ~$500 for an Alpine board until I would become a little bit more devoted to programming the Jag.. Are there PC versions of the assemblers available for the GPU/DSP ? Cheers for any pointers on this stuff.. They might be dimbo questions, but I can't find the answers in any of the Jag forums I've stumbled across..

Glad it was useful If you need any help decipering what it's trying to do or any questions, just ask.. It was a long time ago, and wanted to do more with it but it kind of was left to rot due to work commitments Was a while ago, but I can still remember almost perfectly what it did, and how and why I did certain things.. But it would be good to see it be used for something other than my pitiful programmer attempts at noises.. Pauls right though, you can add the standard TIA audio on it as well, you have on free voice, don't know what it's going to sound like of you start using the 2nd voice for anything, the one being used for the synth playback, probably a bi tlike a tortured cat The idea of taking the 3rd voice of the softsynth would free a huge amount of time up in the kernel, and also in the voice processing code, also a large chunk of zeropage would be available again.. Also it would free a bit more dynamic range on the individual channel levels, might make the EGs sound a bit better, because they're very very feeble with only a few levels available to them.. I did initially experiment with other waveforms and they just don't sound good in 4 bits.. Far too much noise.. And I wanted something that sounded good, without people having to forgive whatever noise and stuff it might have.. The really beauty is the summing method for the square waves which is just beautiful I fully admit I ripped that idea of from Pitfall 2

You really under estimate the the polygon friendly power of Maria my friend In all seriousness, I reckon you could probably squeeze I'Robot onto the 7800.. It'd be a painfully hard job but it could be done, and could look very nice.

Kwix maybe, possibly

erm, blimey! Must check my posts in future, before I hit submit

I Best after I posted, that.. Guess I'm going to have to buy several to bring it up to 20$ minimum

Can anyone recommend a reliable and fast online place I can get a pokey (or 2) from pretty quick ?

I can whack it up somewhere if you want to email it to me ?

ummm, okay but bear in mind this was the state in the middle being distracted months ago.. It's got some horrible glitches in it, but.. bah no more excuses, it's simply VERY work in progress.. Oh, and there's no perpsective transform or clipping on the geometry yet.. The perspective is a small thing, the clipping a big thing I never sent it out to the 7800 list before, simply because it's so early in it's stages, whatever it becomes.. It was simply an experiment in polygon rendering.. And yeah, it's proper polygons, the backside of the cobra model is one 7 edged polygon, rendered in one go There's some odd glitches here and there, dunno why, I don't recall it doing that last time I was playing with it, maybe it did, it was a while ago.. I've no idea if it even works on a real 7800 yet never got that far, all development was done under Mess until I sorted out some Ram cart thing for my 7800.. I doubt it'll run on a real 7800 judging by the other demos and things posted on atariage, that work on mess but fail on a real 7800 until some tweakge is done.. Here's a .a78 and .bin.. http://homepages.nildram.co.uk/~csaba/7800/elite.a78 http://homepages.nildram.co.uk/~csaba/7800/elite.bin There's no user input on it.. That's what I was working on along with general printing and debugging stuff when I slowed to a halt on it.. The config is any need the bin is: SuperCart bankswitching, 8 banks, 16K SuperCart RAM at $4000 PAL.. or if I've missed something out this is the complete .a78 header I use.. ; This automatically generates the A78 header information SEG ROM ORG $0000 RORG $0000 HEADER: DC.B 1 ; 0 Header version - 1 byte DC.B "ATARI7800" ; 1..16 "ATARI7800 " - 16 bytes DS 7,32 ; DC.B "m00" ; 17..48 Cart title - 32 bytes DS HEADER+49-.,0 ; DC.B $00,$02,$00,$00 ; 49..52 data length - 4 bytes DC.B $00,$06 ; 53..54 cart type - 2 bytes ; bit 0 - Pokey cart ; bit 1 - Supercart bank switched ; bit 2 - Supercart RAM at $4000 ; bit 3 - ROM at $4000 ; bit 4 - Bank 6 at $4000 ; bit 8-15 - Special ; 0 = Normal cart DC.B 1 ; 55 controller 1 type - 1 byte DC.B 1 ; 56 controller 2 type - 1 byte ; 0 = None ; 1 = Joystick ; 2 = Light Gun DC.B 0 ; 57 0 = NTSC 1 = PAL ORG HEADER+100 ; 100..127 "ACTUAL CART DATA STARTS HERE" - 28 bytes DC.B "ACTUAL CART DATA STARTS HERE" Anyway, if anyones really interested I can post the source sometime, if only to show how I render the polys and hopefully provide someone with the motivation to do some proper 3D on the 7800, if I never get going again on this that is

Hmm, okay This is nothing special, I just fired up the last binary I had lying around from months ago, so the text is scruffy, the stafield is broken, but this does run around 16 fps.. The general purpose text printing slow it down a bit, but you can see it does the business... There is a frame rate counter buried under that text somewhere, but the last thing I was working on was some generic verison of printf essentially to allow me to display sensible info..

It can and does it not too badly.. I was working on some 3d for the 7800 a few months back, but work demands put a stop to it, and I've never got up to speed again.. I had Elite models rendering full screen at 160 x 160 using up to 23 colours, running at 20fps.. Which isn't too bad for a little 6502.. THe Maria is perfect for drawing polygons, if you can draw it in wireframe you can draw it solid on the 7800 for very little, (I mean very little) extra cost.. Though there's a whole host of other limits.. And yes you need 16K of RAM on the cart to make it doable, which negates the use of a pokey which is a shame (well without some custom bank switching voodoo chippery) I shall when time permits, clean the code up and post something to the 7800 list.. My first goal in mind was something like I'Robot on the 7800, but that was just too much, then a Virus/Zarch/Lander type thing, but that was to special cased to do used a generic polygon system.. It's certainly doable on the 7800, just very hardcoded So I settled on just getting 3D up and running using Elites models.. It's a shame as the 7800 could certainly do some wonderful solid 3D stuff, especially with 23 Colours available to you..

Does anyone know if there's a version of the Elite (the Braben and Bell game) theme for Pokey available anywhere ? All hunts are turning up no results

In that case I think I'll support the stereo outputs. Seems like a good bet if only to give 20 or so people some magic bonus sound extras, and it won't affect mono output except at the cost of a 3/4 extra cycles..

Does anyone have any idea if this is a reasonably large number of people who have their 2600 modded for stereo ? Just curious, since having fallen in love totally with he sound of stereo pokey music[1] and that wicked mixture of 8bit and 16 bits voices I was wondering if my latest 2600 sonic invention would see much stereo playback if I was to add stereo support to it and actually use it in something.. Is there a realistic userbase ? AndyM00 [1] ok, ok I was a non-believer, I used to think SID ruled, but the quality of the tunes muscically on some of the POKEY stuff is amazing.. They both equally rock now Specially the Atarians song on http://grayscale.scene.pl/en_index.php

All that does is attempt to mask the quantisation noise by spreading out the dither generated noise over the entire spectrum and hopefully masking the quantisation and aliasing[1] errors.. With only 4 bits, it's highly dubious imo if the extra noise is worth it. Once your up to silly sample rates, yeah no doubt, but the noise spectrum from a 1bit dither on a 4bit DAC is in my experience horrendous. Even with 44k 16bit streams 1 Bit dither is excessive, typically only .25 or .5 bit dither is used.. Frankly I wouldn't bother on 4 bits, I'd concentrate more effort on getting better, less jittered, less aliased signals out in the first place andym [1] Which is something the 64 did so well. using the Timers to generate the sample/waves instead of integer:fractions to step through makes a huge difference due to there being no aliasing noise present, since you are playing every sample, not missing, duplicating some, so on machines with timers/interrupts you can negate the impact of the aliasing. This is exactly how the Fairlight CMI did it You just let the computer generate a stream of samples at whatever rate it wants, then let an analogue filter take care of it..

I don't think the issue is if then the 2600 can do it.. True if you don't want anything on screen it's a bit easier, but the 2600 still gets a bad lot because of not having any interrupts.. Hence my 'simple' 3 voice PWM system although dead easy to write the voice core, was a royal nightmare to break up into little events less than 60 odd cycles that allow a tune and effects to be processed.. It still came out good with just about every other scanline on the visible screen useable for doing somehting graphics drawing related.. The other issue that saps power from the 2600 is the playing of samples and handling bank switching logic, in addition to the regular fraction/lo/hi byte processing you've got to handle banks as well which having just tinkered with recently, eats even more hard to find CPU time.. Also the misbelief that the 2600 sound is rubbish shouldn't be conveyed.. true 4bit channel levels put it in par with the 800 & C64 in the sample playback league, *but* combine AUDV0 & AUDV1 and you've got 5 bit playback at the expense of a few extra instructions, and it does sound way better, much better than even the C64 could hope for[1]. The final issue to throw into the cooking pot is the playback rate.. Ignoring this the 2600 could theoretically playback 40+ channels, but at about 1000hz, which would sound pooh. All the stuff I've been playing with is targetted at 7680hz which means a new sample every other scanline, anything less and it sounds awful, whilst you could no doubt find yourself a useable few bass notes that didn't alias into oblivion, 7680hz seems to be the point where things perceivably brighten up and gives a useable few octaves of range.. Hence all my stuff is targetting this rate. Just yesterday I was toying with 4 channel playback, and it sounds cool using a simple mod type pattern system, and it stlil leaves almost a full 2/3rds of a scanline available during the visible area, with only 18 (9 pairs) lines in the bottom VBL being non-available for song processing, pattern events, and magic voodoo.. I'll be brain dumping the above to the Stella list this weekend.. But not the real kicker, I had a revelation moment yesterday in this area, and realised that for fixed pitch sample I've now found a kick-ass way to play multi-page/multi-bank samples at the cost of only 5 instructions every 2nd scanline, yeah 18 cycles per channel =) 13cycles if you don't need bank switching (think drums which at 7680hz come out tiny!!), so I think it's time to put together a demo of the 2600 doing something useful with this, and my selected target ? I think Bezerk but with the full monty of ingame voice and sampled sounds without switching the screen off[2] I've attached the old 'pitsound.bin' 3 voice PWM thing Paul mentioned earlier.. Realistically I think the idea of doing a generic SID > TIA conversion is very doable, and was almost my original aim[3], but then I got to thinking that all that time the SID musician where loathing the limits of the waveforms, and how they would have killed for user-definable waveforms, and though what's the point.. Oh for interrupts on the dear old 2600 andym [1] Without it resorting to PWM sample playback methods [2] Though I'm open to other ideas about a test bed for a simple game remake that deserves the kick-ass sound treatment [3] So much so, that I wrote a 6502 emulator that grabbed SID registers from a running .sid and pumped them directly into a 2nd instance of a 6502 emulator running my 2600 code, depositing them into the zeropage as a set of SID register values, so I could let the real SID sound drivers do their stuff whilst concentrating on the SID emulation, intending to just grab the SID registers at the end of the day, and turn them into a pattern system directly from the SID registers.. pitsound.zip