You're mistaken.
SB has access to about 8MiB of RAM MEMORY. The storage capacity on the SD card is NOT LIMITED, the only place where storage capacity is limited is on the UPLOAD SERVER. Let me paint a picture.
A single GRP is 512KiB. This means it takes 8 GRPs to equal 4MiB. I have far more than 8 GRPs on my system, so if what you're saying is true, I must be out of space? I'm not.
0そうだね プレイ済み