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articles:iicplus_smartport_secrets [2018/06/12 20:23] M.G. [Just How Does the IIc Plus Boot Slot 6?] |
articles:iicplus_smartport_secrets [2018/06/26 14:41] M.G. [The 3.5 Floppy Format] |
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| The data field is: | The data field is: | ||
| - | | 5 self-syncs | $D5 $AA $AD | 699 disk bytes | KK KK KK KK | $DE $AA "off" | | + | | 5 self-syncs | $D5 $AA $AD | SS | 699 disk bytes | KK KK KK KK | $DE $AA "off" | |
| In this case, we can see the address and data prologues are the same between the 5.25%%"%% and 3.5%%"%% formats. The epilogues are defined differently. In we are used to $DE $AA $EB, but instead of $EB we have "off"... this is defined in the official documentation as a "pad byte where the drive electronics were turned off." Code that reads a 3.5%%"%% disk should not assume the byte contains anything useful. In fact, ProDOS ignores this byte even when reading a 5.25%%"%% floppy. | In this case, we can see the address and data prologues are the same between the 5.25%%"%% and 3.5%%"%% formats. The epilogues are defined differently. In we are used to $DE $AA $EB, but instead of $EB we have "off"... this is defined in the official documentation as a "pad byte where the drive electronics were turned off." Code that reads a 3.5%%"%% disk should not assume the byte contains anything useful. In fact, ProDOS ignores this byte even when reading a 5.25%%"%% floppy. | ||