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Post by expertsetup on Nov 2, 2006 16:11:19 GMT -5
While working to get cartridge files to run from ram I have had a few problems. I have reviewed the documentation in the Prog.Ref.Guide and Mapping the 64 & 64C.
Can EXROM & GAME be software controlled or are these lines hardware accessible only? Page 263 of P.R.G. states that LORAM,HIRAM,GAME & EXROM are all set high at boot. If GAME & EXROM can not be set with software I am restricted to the maps that have them set to 1 or x for don't care.
Or I could ask are EXROM & GAME set high unless hardware sets them low?
I had not expected Basic to be banked out when I set HIRAM to 0 as I had failed to account for the GAME line state of HIGH.
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Post by Nomen Nescio on Nov 4, 2006 22:07:13 GMT -5
Looking at the c64 scematic diagram in the back of the Programmer's Ref. Guide it appears that while /LORAM and /HIRAM are connected to the port of the 6510 and are therefore software controllable, the /EXROM and /GAME lines are only connected to pins 9 and 8 of the cartridge port, and pulled high with two of RP4's 3.3k ohm resistors. So, no, it doesn't appear that these two lines are software controllable without extra hardware.
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Post by expertsetup on Nov 6, 2006 3:14:34 GMT -5
Thanks for the help, I think I can use some switches added to one of my cartridges. That should do the trick for this task.
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Post by Robin Harbron on Nov 6, 2006 22:26:59 GMT -5
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Post by expertsetup on Nov 7, 2006 16:31:37 GMT -5
Thanks Robin, read a bit last night and will review the rest tonight. The $D000 tricks outlined are very interesting.
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