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benjaminpv | 1 year ago

I always liked the cases where people have broken open ROMs only to find that the compilation process stuffed a bunch of directory and filenames in the silicon. It's funny to think that in a time when literally every byte cost money there's a fair number of carts that have people's FAT entries burned into them.

https://forums.nesdev.org/viewtopic.php?t=17324

discuss

order

toast0|1 year ago

Well... every byte costs money, but it's really quantized. If your game doesn't fit in a power of 2, you have to pay more to get the bigger one (and maybe even a lot more if you also need to include a mapper, plus using a mapper means you've got to adjust your code and what not). But if you're using 75% of your quantized space, you don't need to be that picky.

bryanlarsen|1 year ago

The last time I built a ROM (in the 90's) it had 7 free bytes of space. That was not a coincidence. It was larger than that and then optimized until it hit a nice power of two and then I stopped optimizing.

repiret|1 year ago

It is quantized, but not necessarily to a power of two. RAM and flash sizes of 3x2^n are common even in contemporary microcontrollers, and it’s clearly possible to use fewer R chips then your bus decoder supports in the less integrated computers of yore.

And once you have a project with a fixed amount of ROM, either because the hardware is at a point in its life cycle where you can’t change it, or it’s third-party hardware and you have to use what you get, or because you’re already at your BoM budget, then your software will behave like an ideal gas - it will expand to fill the available ROM. This happens because until you run out of ROM, you will write your software in whatever way is easiest to get your job done. But then once you run out of ROM, you will go back and look for something that you can make smaller. Then you can add a few more features or whatever, until you run out of space again. This process will repeat until you’re done, but your ROM will always be nearly full.

deaddodo|1 year ago

This has happened quite a few times:

https://tcrf.net/Category:Games_with_uncompiled_source_code

It's usually more common on CD games with the directory/file being unlisted, but it's always interesting to find partial source code bakes into ROMs. Last I heard/understood, it was usually as some sort of white space padding; in the case of CD-ROMs and an artifact of the sector-copying mechanism in disk duplicators.

Also, the bytes cost money, but if you have a 32K ROM (because the next lowest size is 16K) and only 28K of data, it's not costing anything extra to fill that space.

JohnBooty|1 year ago

    a time when literally every byte cost money
Possibly overpedantic; please forgive me if so!

Every chip cost money, right? If your game shipped on a single 1mbit EEPROM, it cost the same amount of money whether it was 90% full or 99.99% full. There was of course a cost incentive not to go over 1mbit, or to get your size down enough to fit onto a 512kbit EEPROM.