Roy

You could take it a step further and make both the eyes and hat separate sprites to mimic what is displayed in the arcade game. The eyes would be drawn last to overlay any foreground graphics.

Hard to say. What are the starting display list list addresses? Maybe there is a terminating $00 $00 before address $2342? Does anything change if you zero out $2342 - $2345?

Great stuff! Always been a fan of your music.

Got mine! Thanks Tep and Cpu!

Cool! I want one as well.

For anyone looking for something other than photoshop or gimp, I have started using Aseprite to make my spritesheets. Works great with Bob's program when you specify Aseprite to use its indexed color mode and use a canvas size of either 128 * 64 or 128 * 128 depending on 8 or sixteen high zones. Export as a bmp and feed it to BMP7800. Late to the party here, but thanks for the program bob!

I'm not hiding, I swear! Here's the scoop: I found myself swamped with various projects in various states of completion. I have a really bad habit of losing interest in one thing and going to something else. I'm currently working on a car so I have something to drive before my daily driver gives up the ghost. On the topic of Bullet Festival (name pending) I will need to rewrite huge chunks of code. While working on a second 7800 program, and with the help of various members here, I managed to write a display kernel thats much faster than the one in Bullet Festival. I also have a properly working pokey sound engine that I'll add to it was well; hopefully not sounding like trash this time. Things will be very slow, but I have not abandoned it. I'll open source all my spaghetti code before that happens! Though that'll happen regardless. As I work on more assembly projects (6502 and MIPS) and gain more experience I typically go back and change old programs. In time, you guys can ! Thanks for still being interested though! I really wish there were 10 of me hanging around to get everything finished.

Good to hear, thanks!

Just a quick question regarding illegal opcodes. Have there ever been any cases where such opcodes work on one machine but act erratically on another? Not sure if there are different revisions of 6502s in different 7800s or not. I'm not going crazy with them so far, and have found LAX #$00 ( #$A7 #$00 ) to be handy in a few places, but I'd like a bit of peace of mind they'll work across the board. Thanks in advance!

Found a unit with a smashed shell. Had a hole for the expansion, but it was not soldered in. A1 77 5942454 http://atariage.com/forums/gallery/image/16827-atari-7800/

Here's one: https://atariage.com/store/index.php?l=product_detail&p=1005

There's also a pretty handy wiki full of information here: http://7800.8bitdev.org/ Also contains the document tdididit posted. I find myself constantly referring to it.

I find my method more efficient: ;========================================================= ;==== 7800 Expansion Module BIOS ;=========================================================

Heh, that would make sense! Unless that segment of rom were all graphics, bank swapping $4000 - $7FFF sounds like it will give me more headache than anything. I may just bite the bullet and sacrifice some rom for more graphics and make some cuts here and there. Thanks for your help, guys.

Well, I did have XM in mind with this project. Thing is I have so many sprites, plus needed background graphics, that I don't think I can fit everything if I did both a left and right. I also want to stick to a normal 48K rom size. I did get a routine working that can properly flip the graphics, but I can't find much documentation for accessing the XM features. No clue how to write to external ram! I found something for the xboard, but initial tests crashed the program the second I wrote to $0470 to enable ram. At it's core, without looping through the entire graphics, this is one byte being flipped for 160A mode: lda oldByte and #%00000011 ror ror sta var1 lda oldByte and #%00001100 rol rol sta var2 lda oldByte and #%00110000 ror ror sta var3 lda oldByte and #%11000000 rol rol sta var4 lda newByte clc adc var1 sta newByte lda newByte clc adc var2 sta newByte lda newByte clc adc var3 sta newByte lda newByte clc adc var4 sta newByte I figure something like this, plus additional looping, can be run before the game even starts as to not get in the way. I guess the idea is to sacrifice ram for more rom. (levels!)

One more question! Is it possible to flip sprites vertically? Or will I need to have both a left and a right graphic set for every single sprite in my game? If that's the case, I'm not sure I can fit all my graphics into the game. Edit: Doing a bit of digging, it seems the 7800 can't flip sprites. But I wonder, via XM, if it's possible to copy and mirror the the sprites in ROM to XMRAM? Anyone thought of doing anything like this?

Thanks for the help guys. I'll see what I can put together! TBH this is something I probably should have nailed down from the beginning.

I have been looking at my program structure, and it seems with how I am currently doing things, I guess I'm running out of cycles? The time it takes the engine to calculate changes, setup the DLLs, and play music, seems to spill into drawing time creating difficult to debug glitches. (And God knows what else my buggy engine is creating ) I'm starting on a smaller project from scratch, this time taking care of when I begin to calculate changes. Hopefully by doing this, I can make my SHMUP better/actually work. Before, I would wait for MSTAT at the beginning and end of my infinite loop with all changes being calculated between those two points. The article HERE brings up a really good point that a NMI should be triggered after visible display. This sounds good, so do you guys think the best way to get the most out of the 7800 is to wait for this Display List Interrupt, calculate game changes immediately, then process the DLLs, then finally wait for the start of visible display? I'm assuming without the wait at the end of the program, everything would run too fast? Also the wiki states game logic should be separate from display logic. Does display logic constitute only building the DLLs? Here's a stripped snippet of my main loop: ;End of setting up DL, clearing ram, etc... ;==================================================================================================== ;MAIN LOOP loop: ;Before, I had almost all of my changes happening here. Everything except some background drawing logic... ;How should I use this section if the game logic is calculated at the end of ;visible display? What should go here? jmp loop ;==================================================================================================== NMI: ;This section is triggered by the DLI at the end of visible display. rti Frame timing and sound are my two weakest areas, so I'm hoping the vets here could show me the best way to get the most cycles out of the console and how I should wait for the next frame... Thanks for your time!