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2349
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1 My version of Level III!
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2
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3 The file 'LevelIII.lzh' has a previous (8k block) version, along with
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4 much documentation as to how to set it up.
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5
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6 Quick theory:
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7
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8 The system map has 64k available, of which memory can be mapped in and out
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9 in 8k blocks.
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10
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11 SCF and RBF (and all other file managers) are completely independent. You
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12 can boot OS-9 without ANY SCF modules, and likewise without any RBF modules.
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13
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14 Next idea: map SCF and RBF in and out of the system map dynamically, so that
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15 only one of them is in the map at a time.
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16
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17 The memory map looks like this:
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18
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19 $0000-$1FFF block 0, system direct page, etc.
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20 $2000-$3FFF File Manager Local memory. Mapped in and out as appropriate.
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21 $4000-$ECFF Process/path/device descriptors, Clock, IOMan, etc.
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22 $ED00-$FEFF Kernel track: REL Boot OS9p1
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23
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24 On every system call and IRQ, the 16k block starting at $2000 is mapped
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25 in or out, and the system DAT image changed also.
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26
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27 On boot up, the module 'NitrOS-9' (nitro.a here) sets up the various
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28 maps, and moves up to 16k of SCF or RBF modules into the FM local memory.
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29
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30 Once the system is running, IOMan intercepts F$SRqMem and F$SRtMem calls
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31 from all modules, and allocates FM local memory if the call originates from
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32 there. i.e. RBF allocates a drive buffer, and IOMan gives it local memory,
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33 so a 'smap' would show no change in the number of free pages.
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34
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35 One problem: CC3IO and Windint CANNOT be in FM local memory, as they are
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36 both called via tha D.AltIRQ vector. Every time I try to put them in local
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37 memory, the system crashes, despite all precautions I take. So don't.
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38
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39 The version of OS9p1 here is Level II OR Level III compliant.
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40
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41 IOMan is ONLY Level III, and Nitro.a is the Level 3 File Manager setup
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42 module. '_end' is a dummy module, just a place-holder.
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43
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44 I've just discovered that CC3Disk11 will crash on trying to format a floppy
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45 disk under Level III. It's probably the memory extensions I made to CC3Disk,
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46 and I'm checking it out.
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