Could you explain the above a little more? I have M4 at slot 6 and using your version of the lower rom, so by ising Im4romoff I do not get the 3' back in use. I do not understand the "You could upload AMSDOS to ROM6" part.
If using my modified lowerrom, rom7 gets re-routed to rom6. So even if |m4romoff, it still gets routed to rom6, if there is nothing in rom6, there will be no disc drive available, unless you upload AMSDOS rom to rom6. Notice this is ONLY if using the modified lowerrom.
Also, some questions about your version of the lower rom
1. I did not even try to put m4 rom on slot 7 in my CPC6128. Should I try this before using your lower rom? Would it give better compatibility with the games?
Yes by all means, if your CPC6128 does support overriding rom7 (weak rom or whatever the reason), no need to use the lowerrom. I think compatiblity if using lowerrom or replacing rom7 is very close, not sure. haven't tested that much tbh.
2. My understanding is that lower rom is practically the Firmware. So I have read in other threads about FW 3.15 or 3.16. How does your lower rom compare with it?
It doesn't compare with FW3.x, as it only does one patch, to re-direct rom7 initialization to rom6 for higher game compatiblity, that's all.