Confirm the location of the bootblk kernel

Dear All
i am new to solaris. I am using solaris 5.10 running on my sun blade 150 (sparc). Nowadays i studying about boot process and i am bit confused with the location of the kernel,bootblk. As i found through the internet,
The location of the kernel is

/platform/sun4u/kernel/sparcv9/genunix ---------    is it right?
/platform/sun4u/kernel/sparcv9/unix    ------------    I dont know what this file is?

The location of the primary boot program (bootlbk) is

/usr/platform/sun4u/lib/fs/ufs/bootblk

The location of the secondary boot program (ufsboot) is

/platform/sun4u/ufsboot

One of the document says /usr/lib/fs/ufs/mboot is the secondary boot program.

The above locations will change for 32bit architecture or what? Plese clarify me.