question about dexterity bonuses in the engine

[lac]

I have the mod that gives a nice red ioun stone that grants +1 dex.

 

I'm an elf. I have 19 dex. I try it on, and my dex goes to 20, and my ac does not improve.

Fine, I think, and hand it to xan who can use the help. But then I read the dex manual

at the theives guild. My dex is now 20. I equip the stone, and my dex goes to 21 and

again I get 1 point of improvement in ac.

 

This I think is weird. So I get out shadowkeeper and assigned me several manuals of dex

 

And the results are ...

 

dex 19 (what I started with) ac 0

dex 20 ................................. ac 0

dex 21 ................................. ac -1

dex 22 ................................. ac -1

dex 23 ................................. ac -1

dex 24 ................................. ac -2

dex 25 ................................ ac -2

 

So is this the way it is supposed to be? or is there something weird about this?

[Jarno Mikkola]

So is this the way it is supposed to be? or is there something weird about this?

Read the AD&D rules. So yeah, it's supposed to be like that.