How to format hard disc in JJOS128XL

I just installed the 160gb hard disc. I'm running JJOS128XL. I wanted to move some samples via USB but the MPC is not readable by my MAC, neither could I find the "format" option on the MPC.

Hello!

According to the manual for os128xl as found here http://www7a.biglobe.ne.jp/~mpc1000/jjos_128xl_manual.pdf it reads on page 143:
format from save mode: cursor to upper right field to select the harddisk -> window button -> select format option [F2] -> do it [F5]
format from load mode: cursor to upper left field to select the harddisk -> window button -> select format option [F2] -> do it [F5]

peace, jo