Re: Searching for Krystal Worlds (edited by OUM)
Posted: Tue Aug 01, 2017 12:01 pm
You're welcome Rob, restoring old tapes is often an interesting trip. So it's a win-win, especially as we may soon have a few more tools to restore (very lightly) damaged tapes
Maurice made another new WAV file, with another tape player, and although not perfect it seems much better than the previsous ones. So maybe I'll be able to check if the transfer was correct.
BTW, the checksum at the beginning of the program works like this: it sums the values of each and every byte of the main program, into a 3-bytes long number. Then it compares it to... A stored 3-bytes long number, obviously. If the values are equal, there are no loading errors, otherwise the Oric is reset.
Of course it's not 100% reliable as the 3-bytes stored value may be loaded with errors, or several errors may compensate and give the same value once added. That would really be bad luck to have both such unlikely errors AND a working program... But I'll try and check anyway though - had surprises in the past
Maurice made another new WAV file, with another tape player, and although not perfect it seems much better than the previsous ones. So maybe I'll be able to check if the transfer was correct.
BTW, the checksum at the beginning of the program works like this: it sums the values of each and every byte of the main program, into a 3-bytes long number. Then it compares it to... A stored 3-bytes long number, obviously. If the values are equal, there are no loading errors, otherwise the Oric is reset.
Of course it's not 100% reliable as the 3-bytes stored value may be loaded with errors, or several errors may compensate and give the same value once added. That would really be bad luck to have both such unlikely errors AND a working program... But I'll try and check anyway though - had surprises in the past