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1b75d91002
Add arg to SATARep to specify drive types to show. Add checks in AHCIPortInit to verify port signatures, add helper method to get signatures from port.
63 lines
5.5 KiB
HTML
Executable file
63 lines
5.5 KiB
HTML
Executable file
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<pre style="font-family:monospace;font-size:12pt">
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<a name="l1"></a><span class=cF5> Block Chain</span><span class=cF0>
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<a name="l2"></a>
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<a name="l3"></a>There was a technique on the Commodore 64 where disk blocks were chained together with a block pointer at the end of each
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<a name="l4"></a>block. This is far inferior to having a file allocation table, as in FAT32.
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<a name="l5"></a>
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<a name="l6"></a>The </span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/RedSea.DD.html#l1"><span class=cF4>RedSea</span></a><span class=cF0> file system does not allow files to grow because it only has an allocation bitmap and not a FAT table. This
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<a name="l7"></a>"flaw" is by design. Terry intentionally crippled the operating system, making it a toy with the wisdom that this will
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<a name="l8"></a>prevent commercialization and corruption. The toy spirit of the operating system will be preserved going into the future. Th
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<a name="l9"></a>e vision for this operating system was a modern Commodore 64, which was a fun toy.
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<a name="l10"></a>
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<a name="l11"></a>Doing whole file operations is the ZealOS way of doing thinks. It is the simplest and, ironically, the fastest. It is
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<a name="l12"></a>obnoxious in the characteristic way that ZealOS is obnoxious, flaunting massive modern resources in a way that makes old
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<a name="l13"></a>programmers protest.
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<a name="l14"></a>
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<a name="l15"></a>When doing large, whole-file operations, immediately memory fragmentation is a serious problem, but not so for allocations in
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<a name="l16"></a>the range under a Meg (with occasional larger ones).
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<a name="l17"></a>
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<a name="l18"></a>The file compression scheme in ZealOS only works on whole file operations and the </span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/DolDoc.DD.html#l1"><span class=cF4>DolDoc</span></a><span class=cF0> format cannot have text tacked onto
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<a name="l19"></a>the end, since binary data is at the end.
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<a name="l20"></a>
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<a name="l21"></a>Terry didn't want to spoil fun, so of course offered a way to get awesome performance that is, ironically, superior. </span><span class=cF4>
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<a name="l22"></a></span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskCFile.CC.html#l151"><span class=cF4>FBlkRead</span></a><span class=cF0>() and </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskCFile.CC.html#l214"><span class=cF4>FBlkWrite</span></a><span class=cF0>() allow you to read a block offset from the start of a file. Since files are all contiguous, this is
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<a name="l23"></a>incredibly efficient. You just have to declare the desired file size when you create it with </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskCFile.CC.html#l9"><span class=cF4>FOpen</span></a><span class=cF0>() and cannot change it.
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<a name="l24"></a>See </span><a href="https://zeal-operating-system.github.io/ZealOS/Demo/Disk/DataBase.CC.html#l1"><span class=cF4>::/Demo/Disk/DataBase.CC</span></a><span class=cF0>.
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<a name="l25"></a>
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<a name="l26"></a>If you like, you are encouraged to to do raw </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskBlk.CC.html#l37"><span class=cF4>BlkRead</span></a><span class=cF0>() and </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskBlk.CC.html#l87"><span class=cF4>BlkWrite</span></a><span class=cF0>() directly on a drive. Just get a pointer to a </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/KernelA.HH.html#l3381"><span class=cF4>CDrive</span></a><span class=cF0>
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<a name="l27"></a>with </span><a href="https://zeal-operating-system.github.io/ZealOS/Kernel/BlkDev/DiskDrive.CC.html#l211"><span class=cF4>Letter2Drive</span></a><span class=cF0>() and you are on your way! Your computer is supposed to be a fun toy! You can make an entire partition
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<a name="l28"></a>used for a database, or invent a file system.
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<a name="l29"></a>
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<a name="l30"></a>On the whole, the </span><a href="https://zeal-operating-system.github.io/ZealOS/Doc/RedSea.DD.html#l1"><span class=cF4>RedSea</span></a><span class=cF0> file system with its whole-file-only limitation bring beautiful harmony. It beautifully captures
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<a name="l31"></a>the spirit of ZealOS with simplicity and, ironic speed, since contiguous is fastest.
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<a name="l32"></a>
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<a name="l33"></a></span><span class=cF8>
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<a name="l34"></a>* "Commodore 64" is a trademark owned by Polabe Holding NV.
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</span></pre></body>
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