Just for the sake of completeness: The easiest way I found was to pull down GAME and wait for the first occurence of ROMH after RESET went high. If that happens I can release GAME and who-knows-which-other-unit can take control of the GAME line. This is my way to start a cartridge in C64 mode. To go to C128 mode I just leave GAME and EXROM alone. The only problem left on the C128 is the external KERNAL. I saw strange things happen when I tried to get it running on the C128. The C64 way doesn't work there because of the different bus structure and an annoying but obviously intended behaviour of the PLA (which seems to be more than a PLA). Maybe some of you guys have ideas how I can realize it on that machine. I'll dig out what I found out when I experimented with it if there's somebody interested. I heard that the RAMLink can do it, but I have no confirmation that their implementation does not lead to bus contention and that it actually leaves the RAM below the KERNAL visible on the C128 in C64 mode. Has anybody information about the RAMLink in this concern or has a RAMLink and a C128 handy? Skoe Am Tue, 5 Jun 2012 22:04:21 +0200 schrieb Thomas Giesel <skoe@directbox.com>: > > All, > > I want to add a way to selectively start the C128 mode or the C64 mode > on a C128 to the EF3 cartridge. > > The plan is to assert EXROM until the entry of the C64 mode is > detected and then to release it imediately (or better: leave its > control to the active (emulated) cartridge or KERNAL). > > The first idea was to wait for the first read access to $FFFC, which > seems to work so far and is compatible to the C64. But the CPLD is 99% > full, there are not many macrocells nor routing resources left so I > search for an easier solution (in terms of function inputs). > > Ideas? > > Skoe > > > Message was sent through the cbm-hackers mailing list > Message was sent through the cbm-hackers mailing listReceived on 2012-06-06 22:00:05
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