[Figuring out a 64k bank switching scheme?]

7 hours ago, Ecernosoft said:

64K? Pretty sure you could get 32K if you aren't doing anything extreme.. You're getting into Soni- cough cough, Zippy rom size stuff.

It's compressed fmv. Nuff said! 👀 😅 Lucky me, after all the kernel and data I'll still have an extra 6k to fool around with. Maybe for an intro?

[Figuring out a 64k bank switching scheme?]

Oh thanks! The 2k format should be enough because I'm not banking anything more than raw bytes for the vast majority of the rom and any code that I'll likely add, won't interfere with that 2k static.

[Figuring out a 64k bank switching scheme?]

So I'm trying to make a demo. I want it to be a 64K demo, but I find swapping all 4k of a bank to waste too many cycles when all I'm doing is loading a byte or 2. So I've opted to have a 2k split format similar to what's elaborated here, where the last 2k is static and the rest is bank switched. Problem is, I don't think it exists for 64k... Maybe... I had no issues splitting up the chunks, but I'm not sure how to go about using "hotspots" for a scheme like this.

 

So what I wanna know is: How do these hotspots work? Are they tied to the console, or the rom's chipset?

 

If it's the rom, does that mean I have to define and write my own bankswitching scheme/hotspots? What emulators could I test it on that would work for a case like that?

[Running code at each scanline for PCM voice playback]

Batari basic only uses draw screen. That said, you can jump to the next scanline using WSYNC I think

[DEMO - Impossible Mission (not WIP or Game)]

Flickering is, in a sense, a blending of colors. What I would recommend, is overlapping the first layer with the second, that way those areas blend with each other instead of the background. While the first sprite will still blend with the background, both will blend each other and make the sprites more obvious.

[Vector FMV solution?]

So I'm planning to make a wire frame Vector FMV engine and after some thinking I think I have a method. My intentions in using this will remain private for now, beyond "it's for a demo." However, I figure I'd share my notes on formatting and hear if people believe whether or not this is a viable or if anyone has better methods they would like to share.

 

Few things to go off of before I start.

 

I will be using the sprites (2x wide) alternating between 2 positions per scan-line (may dither). I'll call this the canvas. The canvas will be resolution of 32 by 25, and will be taking up 100 bytes of ram.

 

I do not care if it's optimized. It can take it's sweet time if there are too many cycles but I will be adding a timer later as well as music so I still need to save some cycles real-estate.

 

Will be a stock vcs with bank switching. No extra ram or dpc+.

 

Then end goal:

Draw vector lines to the canvas, or die trying

 

I plan to store vector groups as frames in rom and each vector will be formatted as such.


Line should come in 4 formats


1 Byte for flags (first 2 bits)


Bits 00 is a pixel *

Bits 01 is a vertical vector

Bits 10 is a horizontal vector

Bits 11 is a byte *


*This is what I mean by "die trying" (This is for compression sake.)


If a pixel:
Byte 1 (rom) is the y position and byte 2 (rom) is a number from 0-31 that decides the sprite and pixel


If V slope:
Byte 1 (rom) for the starting pose
Byte 2 (stored to ram) line height (counts down and clears at zero)
Byte 3 is slope input 1
Byte 4 is slope input 2
Byte 5 (ram) Pointer for x coordinates with a bit to say the number of the input.


If H slope:

It will be pre-rendered
The first byte is the starting y position
The second is the total number of bytes in a pre rendered line.
the third and fourth are bytes split up into nibbles for a bitmask lookup table and are ANDed against all the outcomes.
 The remainder is a look up table that starts at the given y position, and whenever the next byte is 0, is set to automatically add the y position to the next byte down (Move to the next byte over if the previous byte contained bit 1)


If byte:

It with set a given y position and variable to a byte. Contains 2 bytes. The ram location to change, and the the byte to store it there.

This was kinda rushed. If there is anything I need to clarify, let me know and I will try to answer and update this post to match if necessary.

My best guess is that this won't be viable for games which is why I'm only using it for an animation.

 

[Counting Bits]

You might be able to generate a table with different bit frequencies to try and do a search of each number of bits. Sort of like Fast Fourier Transform for bits. Not sure how much faster that would be tho.

[Selecting a bit?]

Oh, that was a lot simpler than I was anticipating! Does the setbyte table loop once the variable is over 7 or would I need to reset the variable before I read? Very much appreciated, thanks!

[Selecting a bit?]

So I was wondering if there is a simple way to read and select a bit with a variable.

 

Like a possible implementation of a{6} = b{x}

 

I know course it throws an error for that specifically, but are there any alternatives? I'm trying to setup a 4 way platformer map where the bits are read across the x axis.

[Paint playfield with pfcolors and pfheights. I need help!]

Not without the superchip kernel. I would also recommend using no blank lines if you want the same look.

[Injecting instructions durring drawscreen]

Yeah a quick google search says 16 kHz. I'll probably be fine as long as I make it a priority to update at the start of each Hblank.

[Injecting instructions durring drawscreen]

Do you think it would be more sustainable while still sounding ok if audio updates were on a once-per-scanline basis using the standard kernel?

[Injecting instructions durring drawscreen]

I think I found something here

 

[Sine wave generator for bB]

I made a small program for generating sin data tables to incorporate into programs.

 

Mess around with it here:

https://scratch.mit.edu/projects/614327252/

 

Hope this helps!

[Graphics Glitch (Totem Pole Effect)]

I know if you overflow ram with pfres you can sometimes get a flash of it on screen.

[Injecting instructions durring drawscreen]

I've messed around with it for a while actually. It seems to only update on a per frame basis as is with the stock tia sounds. Works for fades and nice bloops but still has the base restrictions for pitch and such, something I (hopefully) want to tune out if it's possible.

[Injecting instructions durring drawscreen]

I'm thinking a sort of accumulator method than can be used for simple 16 byte looped samples. Simple enough for a saw/square/triangle etc.

[Injecting instructions durring drawscreen]

I'm finally getting back into programming on the vcs again after 4 years and I was curious if it was possible to change variables on the fly while the screen is being drawn or if we're stuck with just drawscreen. Apologies if this is a duplicate of any kind, I did do some digging and couldn't find much besides an implied feature for graphics.

  

On 3/15/2008 at 2:38 AM, batari said:

I had to go back and look at my code to remember what I did.

 

If you use a vector, you lose the ball, and it appears that you can only use player1 or missile1. Also, using a vector seems to prevent you from using a multicolored P1. However, if shifting the missile per line, you can turn the missile on and off per line as well.

 

You can use the above to make the missile into a "fake player" (for example, a 4-wide missile shifted per line might resemble a lightning bolt, similar to that in Tossing Cookies.)

 

You should be able to vary the missile width per scanline, either 1, 2, 4 or 8 wide per scanline instead of shifting, but it appears that you will lack the ability to turn the missile on and off if you do this. I need to do a little more work to get this part working, but in theory it should work.

 

If you wish to use player1 shifted per-line, use of missile1 is limited in sort of a weird way. I'll get into that later.

 

I probably should attempt to integrate this into a beta release of bB so people can play with them and report bugs.

 

Lastly, I am now thinking that "vectors" are not a good name for these, because the term has another distinct meaning in programming. Any suggestions for another name?

 

Also I am aware that it's not possible to change anything while a scan line is being drawn after my previous post.

 

If it's not possible, are there any resources for writing a kernel so I can do that?

 

I wanna try and see if I can feed numbers into the tia volume for better audio control à la pitfall 2

[Playfield resolution doubling with DPC+?]

Naw I'm talking about horizontal resolution. Could we simulate, a smaller pixel width by turning pf pixel bits on/off mid drawing. Or is the hardware too slow?

[Playfield resolution doubling with DPC+?]

I haven't been making anything in the past couple of years for the 2600 but this idea has been nagging me for a while. I'm probably blind and this has been asked many times before, but basically, would it be possible to "race the beam" turning playfield bits on/off mid drawing to "double" the playfeild resolution? Or even simpler, simulate a sub pixel offset for smoother scrolling?

 

I'm sure there are a few drawbacks to this like with reading pf bits directly, but it's worth a try

[How to boxes work?]

They did have an inner structure to them that would hold the cart in place.

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[Robot Zed PLAYABLE DEMO]

Congrats man! That's awesome!?