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Sheddy

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Everything posted by Sheddy

  1. I agree with JetBoot - most likely memory restrictions. Working it in could be very hard without upping the ram requirements or creating a new cart version. Hve - I'm too tired after all that typing in the reply yesterday! EmKay - where are you today?!
  2. Sorry Tempest, no time to do it myself (got to see a man about a dragon...) I had trouble getting the samples into the Atari too. With a bit of trial and error this is what I found on the samples I was looking at: Once you have a .wav file though it's not too bad if you know the original sample size 8-bit/16-bit and rate. There's no compression or anything on .wavs I had to knock up some VB code to convert it to 4-bit, although there may well be some utility to do it already somewhere - my brother's copy of soundforge couldn't do it though! There's about 43 (or 44?) bytes in the .wav header. After this in the 8-bit samples I looked at they were just signed integers (-127 to 128) of the volume level. 0 means quiet, -127 speaker full out one way, 128, full out the other way. I guess the header tells you somewhere whether they're signed or not, but it was easy to tell by the godawfulness of the sound when it was wrong! So simply a matter or some division on each byte to get it to +/-7.5 for the Atari. 4000 4-bit samples/sec sounds sort of OK, 8000 is pretty good. But the sample rate is straightforward to pick - once you know the little secret about sample playing with the screen going.... try something like SAM with a 4k or 8k screen on, and it sounds like he's really drunk - slurring awfully. Why? The DMA fetches for the screen data slow the processor down, and you can't time precisely enough when to do the next sample, without your ears noticing. So you need something external for the 6502 to get its timing from. Maybe you can try Pokey interrupts - but they seem to get affected by the DMA fetch too! (and no emulator does them properly yet either). That only leaves a couple of things that change quickly enough and reliably enough to use to re-synchronize the processor - either WSYNC or VCOUNT - which aren't affected by DMA. These registers get changed at the end of each scanline. VCOUNT changes every other scanline, and goes from a value of 0 to 130 (NTSC TV) in each TV frame. 60 frames in a second. So 60*131=7860 changes per second. Voila - 7860 samples a second is not too shabby a number to choose - or 3930. Well, jeez, I said a bit more there than I intended. Sorry about that everyone else - turned into more of a programming thing there.
  3. Definitely worth turning into a book IMO. (Still can't beat the user interface of a book) You've a great way of explaining things, which makes it SEEM almost straightforward to use the 2600!
  4. Cheers for the link Nukey. Somehow missed that thread - Fascinating stuff. Could have saved myself asking Andrew some numbskull questions about his excellent Fu-Kung work and picture demos with all those good explanations there
  5. I agree with Eric, Frustrating though it is, a re-write is no bad thing - you often end up with something better. If it was easy, you wouldn't get any real satisfaction out of it either. It was 8 years before I picked my project up again with a complete re-write - no need to rush! I constantly re-write code if I think of a better way to do things (to the frustration of anyone actually wanting the game finished, I'm sure!)
  6. Another cross-assembler for the 8-bits. Atasm - Mac/65 compatible too. http://www.cs.utah.edu/~schmelze/atari/atasm/
  7. That's good to know. Thanks!
  8. It's looking real good Ron Have you any plans to make a (maybe cheaper) emulator only version for download or something like that? I'm thinking a lot of people without a 5200 - like most of us Brits, who are nonetheless interested, could miss out otherwise. What do you think?
  9. Yeah, would have loved some of those instructions! Lots of embedded controllers and the like use cores based on 6502 or 68000 and even better now. Also tend to run much faster. Seems kind of weird that the swimming pool controller or the washing machine can dump on our old home computers from a great height, computing-power-wise
  10. how ever much of an Atari fan you are, you've got to admire the C64 for its sprites (sooo much better than player/missiles), SID for music and the color ram on the "character" modes.
  11. oh, that's what I thought you meant to start with for a split second!...but, no he couldn't have meant that...of course, on reflection, yes, that could have been very handy indeed definitely an award of some sort required... 6502 hack award???!
  12. That would be nice - so turning it into a 3 byte instruction for just this special case? Certainly hard for the proc if the instruction is variable length - I'm not a hardware person, but I think that would make the decoding hardware a lot more complicated. I'd have liked a whole range of conditional jumps, something like jeq $nnnn, jcc $nnnn etc. Mind you, given the chance to change the 6502 instruction set....there's just so much that would be nice to add, change or get rid of!
  13. I read somewhere that the early 400/800 models had the 6502B chip which doesn't support these extra instructions. Atari had the 6502C made coz it allowed them to leave out some extra support chips; something to do with WSYNC I think...pulling down the HALT line on the chip??? All the models after that definitely have the 6502C. Only problem arises is when people have replaced the processor with some super 16 bit CPU upgrade which has 6502 instructions...they don't have the 6502C instructions... I've only used the LAX (),y instruction. Like Thomas says, saves doing a TAX. Very handy in a time critical sprite routine for masking. EG lax (data),y ora (screen),y and mask_table,x sta (screen),y Frankly I've never had the ingenuity to figure out a use for the others - luckily we don't have to work to exact cycle counts on 8-bit Atari computers - some of the extra instructions seem pretty bizarre, and I guess they are mostly just obscure side effects rather than any deliberately designed instructions, although maybe you can do something like Nukey mentions...not sure quite how for most things though...some of the demo coders might know different though.
  14. Certainly worrying....looks like the "discussion" got a bit heated! Out of curiosity, are you working from one of these sources or from scratch? Mr. Braben seems like he may be reasonable if permission is asked for - so it could be worth asking....or maybe you should just keep a very low profile!
  15. thanks MK - guess I had missed them somehow! Now I can hear your tune
  16. very nice, but now the emulator code is removed, you can't play back the song as you are composing. not all of us can hear the music in our heads! Anyone know enough C to produce the DLL's required by the prog for playback?
  17. Paul Woakes also did Mercenery... v.cool too.
  18. Mr Do Encounter I'd have to go for these too. Don't forget Joust though - Surely one of the most fun 2 player games.
  19. Cheers JetBoot you found any more time for your projects, (and what is Nazgul)? Cafeman! Looking forward to Adventure II, and hoping for Koffi on 8-bit - you know we never got 5200 in the UK? There's nothing really that different about the 130XE, except it has 128k RAM, which is switched in and out in 16k banks. There's an expansion port, but that's about it as far as I know. Oh, and you only get the 2 joystick ports like on the XL series. Thanks! I'm quite pleased with the sprite routine, it seems to have worked out quite well, although the game will only run at 15fps instead of 60 because of the size of stuff. Everything is bg graphics apart from your man at the front of the screen, which is all the sprites. It's in Antic mode D, but there are 2 of them which are interlaced to give more colours. It flickers because of this, but the sacrifice for the extra colours seemed worth it. The screenshots are a composite of the 2 interlaced screens.
  20. Hi all, just to let you know I've posted a work in progress update for Space Harrier 130XE (at www.sheddyshack.co.uk as usual). I must have gone totally mad as you'll find the latest source code there too. (For those who can't sleep at night only)
  21. Checking out comp.sys.atari.8bit, it seems some people have taken up the challenge of porting it over to work on Windows. This is great news, as Atari++ is the only 8-bit/5200 emulator at the moment that deals with changing colours and doing stuff mid-scanline properly. Things like Master of the Lamps will work properly now.
  22. Good point about the Fairchild F, had forgotten about that. Thanks. Wonder if you could class the pong clones as consoles though?
  23. I got sent the following e-mail. I figure the 2600 has got to be one of the oldest. Maybe some of you UK 2600 owners have still got their original console from back then, or know of someone... of course you all kept your sales receipt.... Don't know why it got sent to me, as sadly I've been without my 2600 since the mid-80's and still haven't got myself another wooden 6-switch yet From : "harriet" <[email protected]> Hi My name is Harriet and I am a journalist for SWNS. We are the Largest Independent Press Agency in the UK. I want to do a fun piece for the national newspapers and I am looking for the oldest working games console in the UK. Do you know anyone with an old one who may want to help me out and appear in the newspapers for a fee??? Regards Harriet Crosse (SWNS)
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