That's what Square claimed, but it's a boldfaced lie.
Items are stored server-side, not on the PS2. If it was stored on the player-side, you'd be seeing people running around with hacked items all the time. There should be little to no memory usage on the PS2 to hold items.
Likewise, the same items that would have been stored in 160 slots, are instead stored on a character and a mule in 2 sets of 80 slots. Once again emphasizing that there was no difference in memory usage.
There was no memory issue, only lazy programming.
Im not so sure on that one. The game, despite the info being on yonder side of server still needs to hold the information on the client-- or you wouldnt see the inventory at all! While I agree a set of 80 seems small, we can never be sure what info is required for each item. I think the problem is that SE has all of the PS2's memory in use at any one time save for a small portion reserved for inventory, not anticipating needing more. This is why we have many containers but never over 80, as the PS2 cannot retain info on 80 items in a collection at one time.
Here's the thing about items in FFXI: in order to display the item's data, the game needs to load the item's entry from the item DB (the DB itself is too large to fit in the PS2's RAM). Each DB entry takes up 3 KB (most of that 3 KB is taken up by the item's icon). For performance reasons, the entries for your inventory and one storage space (safe, locker, storage, or satchel) are cached in RAM (because loading them as needed of the hard drive is slow, and doing so from the server is slower still). 80 storage items + 80 inventory items therefore takes up 480 KB, which is about 1.5% of the PS2's RAM.
However, the PS2 RAM is very cramped. Because the PS2 has very little video RAM, all texture and model data has to be stored in main RAM. Graphics data for each zone takes up around 10-12 MB; graphics data for players and mobs can run up to 1/4 MB each, and with a cap of 50 displayed at once, there goes another 12.5 MB.
Take off another 1 MB for the program itself, and there's only 6.5 MB of RAM available, which has to hold inventory, animation and visual effect data, music and sound data, cached chat logs, and an ever-expanding auto-translate dictionary, and it becomes easy to see how inventory size becomes constrained by PS2 memory issues.