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Re: Easy words for boot sector ?
Posted by: leonard Mar,18.2017-23:04 

First sector of a floppy (sector 1) contains information about floppy geometry & filesystem ( FAT size, number of side, number of sectors etc). All these informations are located at the begin of the sector (out of my head, first 32 bytes). All other bytes are generally useless.
But the TOS added a possibility: if the sum of all words of the sector is $1234, then the TOS consider the bootsector contains code and JUMP at offset 0 of the boot when you start the computer.

If you want to put some code in the boot sector, but you want TOS of FastCopy is able to say "hey this disk is 80 tracks, 10 sectors", then you have to keep these first 32bytes, that's why you only have 480 bytes left.
If you don't care about TOS knowing the drive geometry, then you can use 512bytes for code!

Last, if you want TOS jump to your code, you have to make the magic $1234 checksum, so at best you only have 510 bytes for your code.





[All messages in this thread]

Topic Posted by  Date 
Easy words for boot sector ? s_t_s Mar,15.2017-10:35
  Re: Easy words for boot sector ? ggn Mar,15.2017-10:54
    Re: Easy words for boot sector ? s_t_s Mar,15.2017-11:24
      Re: Easy words for boot sector ? ggn Mar,15.2017-14:30
      Re: Easy words for boot sector ? evil Mar,15.2017-19:30
        Re: Easy words for boot sector ? s_t_s Mar,17.2017-09:36
          Re: Easy words for boot sector ? leonard Mar,18.2017-23:04
            Re: Easy words for boot sector ? s_t_s Mar,21.2017-23:01
              Re: Easy words for boot sector ? leonard Mar,22.2017-02:28
                Re: Easy words for boot sector ? ggn Mar,23.2017-10:29
            Re: Easy words for boot sector ? PeyloW Mar,24.2017-23:23
  Re: Easy words for boot sector ? s_t_s Mar,15.2017-11:17
  Re: Easy words for boot sector ? Alien / ST-CNX Mar,24.2017-07:35
    Re: Easy words for boot sector ? s_t_s Mar,24.2017-19:59
      Re: Easy words for boot sector ? Alien / ST-CNX Mar,25.2017-01:04
    Re: Easy words for boot sector ? PeyloW Mar,25.2017-20:04
      Re: Easy words for boot sector ? ggn Mar,26.2017-17:55
      Re: Easy words for boot sector ? Leonard Mar,27.2017-01:39
        Re: Easy words for boot sector ? ggn Mar,27.2017-07:36
          Re: Easy words for boot sector ? s_t_s Mar,28.2017-19:38
            Re: Easy words for boot sector ? ggn Mar,29.2017-07:47
              Re: Easy words for boot sector ? s_t_s Mar,29.2017-10:26
                Re: Easy words for boot sector ? s_t_s Mar,29.2017-10:27
                Re: Easy words for boot sector ? ggn Mar,30.2017-07:56
                  Re: Easy words for boot sector ? s_t_s Mar,30.2017-09:02
                    Re: Easy words for boot sector ? Alien / ST-CNX Mar,31.2017-20:21
                  Re: Easy words for boot sector ? s_t_s Mar,30.2017-09:04


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