Very interesting. Taking the instructions of the original and modifying them likely does not prevent copyright claims. Remember the clean room approach to IBM BIOS that Compaq took? So if they had documented the addresses and what each function did, then another team wrote the code from scratch, it might be ok. But shuffling and tweaking existing instructions wouldn’t. -Nate > On May 18, 2019, at 3:29 PM, Jim Brain <brain_at_jbrain.com> wrote: > >> On 5/18/2019 2:34 PM, Marko Mäkelä wrote: >>> On Fri, May 17, 2019 at 08:43:13PM -0500, Jim Brain wrote: >>> Given Pete's response about putting a JD ROM in and the thing refusing to work, does anyone on list have the drive and would be willing to test? >> >> Could it be that some address or data lines have been swapped on the circuit board? In that case, you would have to transform the EPROM image accordingly. It should be rather easy to figure out the mapping by examining the raw image of the original ROM. >> >> It is an interesting idea that permuting some instructions would thwart copyright claims. I wonder if that would really have held up in court. Even back in that day, there had been some disputes, such as one between Commodore and Bally Midway, regarding Radar Rat Race aka Vic Rat Race aka Rally-X. >> >> Marko >> > I don't think it's an issue with BlueChip ROM, as no address or data lines are swapped. The FSD-1 had a data line swapped (D3/D4, as I recall). I doubt seriously it would stand up to copyright claims, as the correct code can be pulled from the bus during operation, which would shew the correct code. > > -- > Jim Brain > brain_at_jbrain.com > www.jbrain.comReceived on 2020-05-29 22:02:57
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