The EPROM Pac is a special cartridge for the Sorcerer that was intended for power users to put their own software on a cartridge.  EPROMs are Erasable Programmable Read Only Memory chips, which unlike regular ROMs means that the can be erased and rewritten.  The user would have to have the means of programming the EPROMs (up to 16K) along with the correctly compiled software.  Although this sounds a bit daunting to the regular user, the EPROM Pac was a powerful and useful bit of hardware to those who had the ability to use it.  Originally the EPROM Pac could only use 2716 (2K) EPROMS but the manual mentions that it could be modified to handle 2708 (1K), 2732 (4K), and 2764 (8K) EPROMs as well.  The EPROM Pac cost $49.