MPC and keyboard midi question. ????

so I hooked an old yamaha psr520 keyboard up to my mpc but I have a question.

I was changing through the sounds on the keyboard using my mpc (from the main screen in the pgm: field) the number can go up to 128, but there are more sounds on the keyboard then just 128, there is 149. So I looked at a link in the binger0 newbie post (www.borg.com). The link explained how there was standard pgm numbers for keyboards and also for drums. It listed them (i cant remember the numbers and the link is down tonight) it said like piano: 1, electric piano: 2 ,all the way till 128 (towards the end the sounds are a helicopter and a gunshot) anyway these arent the sounds that I hear when I play the keyboard by itself. Its like when I choose the pgm with the mpc I am given different sounds. On top of that those midi pgm numers dont include any drums and the keyboard has all sorts of drum sounds on it but i have yet to be able to access the drum sounds (I asked on the board earlier and someone told me to change banks on the keyboard but this keyboard has no banks. So how do I play the sounds I hear when playing the keyboard by itself without the mpc?

I hope my post is clear enough

I got a PSR too, but it's a 250 or something. I don't know. You should be able to change sounds on your keyboard on the keyboard itself. You don't need the MPC for that.