On 12/18/2013 01:38 AM, Jim Brain wrote: > On 12/17/2013 4:24 PM, Gerrit Heitsch wrote: >> On 12/17/2013 10:59 PM, Bil Herd wrote: >>> Several of the times when I tried to "clean up" this kind of thing for >>> the C128 I would come across a compatibility issue; we found that third >>> parties had used the glitches on IO lines to latch R/W and that some >>> carts >>> like the Magic Voice cart would drive the bus at unexpected times >>> including the high address lines (They would toggle /GAME and /EXROM >>> dynamically when the system had been designed for them to be solder >>> jumpers). Eventually I stopped trying to "improve" it and try to >>> learn to >>> "live with" it. >> >> There are other carts that are guilty of that... The feature of the >> Easy Flash 3 that lets you use a KERNAL on the Expansionport without >> having to remove the internal one or any internal soldering needs >> dirty tricks like this. >> >> See here: >> >> skoe.de/kernal/kernal-cartridge.pdf >> >> Some people like it, I don't. > Everyone's entitled to their opinion, but I think the *hack" in EF3 is > what groups like cbm "hack"-ers would appreciate. One could say the > same thing about the trickery and abused done to the poor VIC-II to > remove borders and such. For that you stay within the timings of the C64, you just have to write to registers at the right time. > Using the MMU backwards to check for ROM at $e000 and then switching to > Ultimax mode on access to present the KERNAL is a significant hack I think. Yes, but for that you have to do things that are outside the normal C64 timings. You have to make a lot of assumptions on parts speed and do multiple things within a clock cycle. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2013-12-18 01:02:01
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