The Micropolis drive controller is in the expansion unit. It includes two PROMs that hold the 256 bytes of boot code. This is executed from the Sorcerer monitor with GO BC00. I found that the code was not executing as expected and when i compared with PROM images to those discovered on in the TOSEC:
https://archive.org/details/Exidy_Sorcerer_TOSEC_2012_04_23
These 82S129 PROMs are quite difficult to find, so i made up an adapter board for an EPROM. I used wire wrap sockets to connect into the existing PROM sockets. This has been working fine.
