X16 largest file size

xanthrou · Post by **xanthrou** » Tue Feb 09, 2021 7:59 am

What is the largest possible file size on X16 that theoretically could be achieved?

Ender · Post by **Ender** » Tue Feb 09, 2021 8:56 am

I'm not sure what you mean exactly? Like, the maximum size that could be loaded into lower memory all at once without overwriting anything essential? Probably from $400 to $9F00, so around 38.75KB. If you write an algorithm to, for example, read one byte at a time and copy them into RAM as you do, it would be that 38.75KB plus the 2MB of maximum RAM, so 2.03875MB. Of course, it would be dangerous to assume you have all 256 RAM banks available, as some, or most, users wouldn't actually have that much installed in their machine.

kelli217 · Post by **kelli217** » Tue Feb 09, 2021 9:00 am

I can set an upper bound for you: 4GB. That's inherent to FAT32 as a filesystem. Whether or not the ROM can even begin to support files of that size, I couldn't venture a guess. I did read some of the docs, and the size of the filesystem itself can go up to 2TB. That's the limit for FAT32 anyway, so the file size limit is probably the same, too.

xanthrou · Post by **xanthrou** » Tue Feb 09, 2021 9:06 am

5 minutes ago, kelli217 said:

I can set an upper bound for you: 4GB. That's inherent to FAT32 as a filesystem. Whether or not the ROM can even begin to support files of that size, I couldn't venture a guess. I did read some of the docs, and the size of the filesystem itself can go up to 2TB. That's the limit for FAT32 anyway, so the file size limit is probably the same, too.

X16 uses FAT32?

kelli217 · Post by **kelli217** » Tue Feb 09, 2021 9:24 am

17 minutes ago, xanthrou said:

X16 uses FAT32?

It does for the SD card, yes.

TomXP411 · Post by **TomXP411** » Tue Feb 09, 2021 4:56 pm

Yes, the X16 uses FAT32, and the file seek command takes 4 bytes. So it’s possible to create and make use of a 4GB file.

You obviously can’t load 4GB into RAM, but that’s part of why the Seek command was introduced - to allow you to dynamically loads portions of the file you actually need, as you need them.