ral-clan wrote:I am really a novice when it comes to understanding how all of this works, but I believe the PROMQUEEN cartridge maps both the EPROM you put in it, and it's own built in 4K of RAM into the VIC's memory map (via dipswitches - see picture above). There is also a switch on the PROMQUEEN you have to flip at some point. Again, I am not sure what I am talking about, so I will just scan the whole page from the manual relating to this and post it in this thread of discussion (maybe tommorow if I get a chance).
Mapping the EPROM for reading may be good but certainly not for burning data into it.
When the VIC writes to a memory cell, the data access last half of a microsecond period or 500ns. Writing one byte into an EPROM that old way can take up to 100ms or 100'000 times longer than that and it must be uninterrupted.
The "proper" way to burn data into an EPROM from a VIC or C64's cartridge port is either to use one or more communications chip such as 6522s available on IO lines or a set of logic latches such as 74LS373s.