You do realize, the PB100 is a macintosh portable with a completely redesigned power circuit, right? Oh and the display controller is different as well I believe. Everything else electronically is the same. They did remove the MISC GLU because the PB100 uses regular DRAM instead of SRAM/PSRAM, and they switched to 85C80 SCSI/SCC because of space reasons. 

But the core logic, main GLU, is identical.