Following with the Rombank explanation, a new option has been added on the
10 August 2020 update, emulated Roms in Ram. This is not new to the Enterprise, it is a characteristic of EXOS, but SF3 can do the process automatically.
A Rom can be defined on the Rombank, let's say EPDOS21.Rom on 04-05 segments, by the procedure of renaming a copy of the Rom file as ROM004.BIN inside the EP/ROMTABLE/BANK000 directory inside the SF3's SD. Remember to also add a ROM004.TXT file explaining the real name of the Rom.
Then, you must edit the INI file and add this line to the Ram definitions:
EPRAM[#04-#07]
On the actual CPLD SF3 firmware, the Ram/Rom zones can't be smaller than 64KB, so you only can define X0-X3, X4-X7, X8-XB, XC-XF zones, not individual segments. This means that the Romtable has selected as write-protected(Rom) the whole 04-07 cartridge area, not only the needed 2 first segments, 04 and 05.
At switch-ON, the INI file is executed just after the Rombank definitions so the INI file will un-protect the already injected Rom, leaving it as Ram filled with the Rom data, and 06-07 segments as the emulated SRAM chip. Once the SF3 initialised, EXOS will start searching for Roms and Ram, and will read the Rom header on 04, adding it to the Roms list.
EPDOS2X also needs some more configuration executing some batch files from a floppy disk(EXDOS needed), I am not going to continue with it, but at least the special hybrid cartridge can be simulated with the SF3. This is theory, sorry.... I still have not tested it...
Once the experiment being over, remember to erase ROM004.BIN on the Romtable dir and the Ram definition line on the INI file.
--------
I understand that the concept of "write-protected Ram" instead of ROM can be strange, but it is how the SF3 works inside. And I also know that EPDOS2X was not the best Rom example to demonstrate the use of emulated Roms on the SF3....
On Enterprises provided with the Quick Ram Test from Zozo, the emulated ROMs can be erased from system if F4+Reset are pressed while on the Ram test.
-----
Why I have not used the Rom Manager program to do the EPDOS thing? because the Basic program only deals with the 60-7F zone, as it was inherited from the CPC.