Re: Sunraycer Question

["Bryan Parkoff" <nospam@nospam.com>]

Michael,

    Yes, I understand.  If the programmer or someone succeed to support copy 
protected Disk II emulator, it is possible that Sunraycer may be able to run 
in copy protected emulator.

Bryan Parkoff

"Michael J. Mahon" <mjmahon@aol.com> wrote in message 
6aqdnYjKc44KdjHfRVn-oA@comcast.com">news:6aqdnYjKc44KdjHfRVn-oA@comcast.com...
> Bryan Parkoff wrote:
>>     I know the fact that Sunraycer will not run in any Apple II emulator 
>> unless track $19, sector $0A, address: $17 is modified from $E7 to $F7 
>> before it will run fine on any Apple II Emulator.
>>     They state that it requires to have real Apple II hardware for 
>> rotating disk timing which it is always unimplemented.  Is there a 
>> possibility that we should implement rotating disk timing so Sunraycer 
>> will work on one Apple II emulator without modifying Sunraycer's disk 
>> image?
>>     Is there a way that Copy II Plus can measure Disk II speed correctly 
>> which it should be at 200.1 ms instead of going up to 220 ms or greater 
>> unless we implement the rotating disk timing properly?
>>     Any suggestion is welcome.  I appreciate this.
>
> Thomas Lai, who did the original modification, has looked further
> into the incompatibility with emulators and has found that it is
> a result of the "residue" of a disk copy protection method left
> on the disk after deprotection that was "sufficient" to allow it
> to run on a real Apple II.
>
> The residue in this case is a nibble count routine that does not
> exit until it finds a particular disk nibble in its scan.  The
> original deprotector simply disabled the equality check on the
> nibble count, but did not remove the counting code.
>
> The best solution in such cases would be to remove completely
> the copy protection, so that it is not an issue.  Since this
> may be onerous or beyond the capabilities of some who just want
> to play the game, it would be sufficient for an emulator to
> simply return an 8-bit counter value whenever the disk read
> register is accessed, since that will lead virtually any nibble
> scan routine to exit promptly.
>
> -michael
>
> 8-voice music synthesizer using NadaNet networking!
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