The BBC Master has a MOS ROM that includes 8 pages of ROM.
This are MOS, Terminal, View, ADFS, BASIC, ANFS and DFS.
There are a few updates for this ROM’s and there are compability issues.
You cannot easily change the ROM because it is 28 pin socket and EPROM or FLASH has at least 32 pin.
This is why I have designed a simple ROM converter/switch the can hold up to four different set’s of ROM’s.
This design is one of the smallest and can use either 27C020/040 or flash 29C020/040.
This are still easy to get hold on.
You can buy a DIY kit from me with all parts or you can by it ready build and tested.
I will also offer a FLASH with the ROM’s preinstalled.
If you want more then one please as for price.
The Flash is a 29c040 with ROM’s found at mdfs.net
MOS 3.2 with fixes
MOS 3.5 with fixes
MOS 1.2 with ROM’s converted to Master
If you need a special ROM combination please let me know.