C64 Games memories - Bubble Bobble

In this video I look at Commodore 64 Bubble Bobble and how its software sprite rendering works and demonstrate how the code can render extra sprites.
github.com/martinpiper/Debugg...
GMA disk loader: • Disk fast load digital...
00:12 Introduction
00:29 Disk "Bleep load"
01:07 Memories
01:21 Looking for hardware sprites
01:32 ... and software sprites
02:38 More character masking
03:54 Starting to see dynamic characters
05:16 Two character sets!
05:48 Lots of hardware sprite frames
08:18 Memory write debug, for character sets
09:55 Using the machine code monitor
12:35 Backup screen data
14:15 Dynamic characters for each level
15:26 Collision data
18:18 Finding software sprite code
35:56 Finding frame, xpos and ypos tables
39:01 Rendering new sprites!
41:50 Technical summary

[@Sidchipp]

Martin, your ability to reverse engineer these games is unparalleled. I love the narrative approach as you figure it out, well done. Pretty nutty the bubbles are drawn using chars mixing in the background data.

[@cpu_UP]

Really interesting. Never played much the game but now I understand that the bobbles were not multiplexed sprites.

[@Sumaleth]

Really impressive engine. One thing that surprises me is how many of these games use a double-buffered screen. Back in the day I thought I had managed to pretty much rule that out as a viable way to make a game just because of the amount of memory it used, but clearly I got that wrong.

[@villehursti]

These deepdives into C64 games (this and IK+) just blow my mind. I have wondered and guessed for years how they were actually made. Nice to finally see that I wasn't too far off. Thanks Martin!

[@MartinPiper6502]

Glad you like them!

[@aNdy_AL_C0S]

I dug around in the code for this myself some years ago. So very cleverly done and probably way beyond what I would be capable of, even with the ease of development because of the modern tools today! Thanks for the breakdown though!

[@delgilchrist]

Very interesting stuff as always! Thankyou for doing this!

[@igork3522]

Thank you for making this videos and making access to the code!

[@frodbolf]

FOND memories!

[@victorwidell9751]

The "separate collision buffer" also contains the bubble wind current.

[@MartinPiper6502]

oh cool! :)

[@TheStuffMade]

Nice reverse engineering 👍I always thought Bubble Bobble was an excellent conversion for the C64, but I never imagined they were using quite advanced software sprites for all the bubbles. It's very impressive, especially considering what they had to work with back in the mid/late 80s.

[@cruncherx86]

Hi Martín, good morning! As always fantastic review. Sorry, you surely pointed out previously, but let me ask what kind of environment do you are using for “scraping” games? I started to mess with games with rather simple tool (vice monitor, 64 java based disassembler) but your tools are incredible. Any hint to let me improve?

[@InternetVegetable8541]

Google "ICU64"

[@c64customs]

Very interesting video as usual, thanks for making it. I wonder wether Bandits works in a similar way.

[@MartinPiper6502]

I'll add it to the list...

[@geehaf]

Great explanation - as always! How about Barbarian - I think that also used SW sprites?

[@MartinPiper6502]

it's on the list!

[@jameswelch2850]

Thanks for these videos. Please do Zybex or Soldier of Fortune (Graftgold) if you can!

[@MartinPiper6502]

Thank you for the generous support. They're on the list. :)

[@retro_noix]

In two player mode, there must be at least 32 bubbles floating around... did you try that off camera?

[@LordmonkeyTRM]

If a screen takes 16kb of data to fill does that mean double buffering is using 32k?

[@MartinPiper6502]

A VIC bank is 16KB, the screen takes about 1KB, ignoring the characters and colours.

[@victorwidell9751]

Replace the sw rendering with hw sprite multiplexing!

[@epicon6]

0:12 It’s Bubble Bobble, not Bubble Bubble

[@MartinPiper6502]

I say Bubble Bobble, but the auto-captions are wrong.

[@saganandroid4175]

"Software sprite"????? B U R N T H E W I T C H. "software sprite" is an oxymoron.

[@arlasoft]

Yawn. That's what most developers call them, whether or not the term is technically correct, it has stuck and when you say 'software sprite' everyone knows what you mean. If there was a more succinct, pithy and accurate term for them, we'd already be using it.

[@MartinPiper6502]

We do tend to call them software sprites... csdb.dk/forums/index.php?roomid=11&topicid=25151&showallposts=1