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1 <!--
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2 The author has not been contacted about adding this article to the
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3 documentation set.
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4 -->
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5 <article>
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6 <articleinfo>
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7 <title>The OS-9 Boot Process</title>
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8 <author><firstname>Alan</firstname><surname>DeKok</surname>
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9 <affiliation>
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10 <address>
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11 <email>aland@striker.ottawa.on.ca</email>
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12 </address>
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13 </affiliation>
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14 </author>
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15 <revhistory>
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16 <revision>
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17 <revnumber>1</revnumber>
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18 <date>Tue Apr 29 21:53:46 EDT 1997</date>
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19 </revision>
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20 <revision>
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21 <revnumber>2</revnumber>
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22 <date>13-Apr-2003</date>
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23 <revremark>DragonDOS boot added</revremark>
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24 </revision>
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25 </revhistory>
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26 </articleinfo>
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27 <section>
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28 <title>COCO Computer</title>
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29 <orderedlist>
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30 <listitem><para>Typing 'DOS' at the DECB 'OK' prompt loads in track 34 off of the disk.</para></listitem>
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31
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32 <listitem><para> Track 34 gets loaded into address $2600, and execution of code
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33 starts at $2602.</para></listitem>
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34
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35 <listitem><para> $2602 contains a BRA to the execution point of the REL module.</para></listitem>
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36
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37 <listitem><para> REL copies the boot track ($2600 to $3800) to address $ED00, and jumps to
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38 another routine inside of REL, at the new address.</para></listitem>
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39
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40 <listitem><para> REL then jumps to OS9p1, which sets up system variables, the system
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41 memory map, system call tables, IRQ & SWI setup, and calls BOOT.</para></listitem>
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42
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43 <listitem><para> BOOT reads sector $000000 off of a disk, and finds out where the
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44 OS9Boot file is.</para></listitem>
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45
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46 <listitem><para> BOOT requests system memory for the size of OS9Boot, seeks to where
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47 OS9Boot is, and loads it directly into RAM.</para></listitem>
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48
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49 <listitem><para> It then returns to OS9p1, after setting up pointers in low memory to
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50 the OS9Boot file.</para></listitem>
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51
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52 <listitem><para> OS9p1 links to OS9p2, and executes it.</para></listitem>
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53
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54 <listitem><para> OS9p2 sets up more system calls, links to the clock module, and
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55 calls it.</para></listitem>
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56
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57 <listitem><para> Clock sets up some more system calls, starts multitasking, and
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58 returns to OS9p2.</para></listitem>
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59
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60 <listitem><para> OS9p2 then does F$Chain of 'CC3Go'. This prints a start up banner,
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61 and runs your 'startup' file through a shell.</para></listitem>
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62 </orderedlist>
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63 </section>
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64 <section>
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65 <title>Dragon 64</title>
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66 <para>
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67 DragonDOS BOOT (when you type BOOT)
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68 loads sectors (numbered from 0) 2-17 (4096 bytes) into
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69 RAM at location $2600. The first two bytes of sector 2 must be ASCII 'OS'
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70 for this to work. It then jumps to $2602 and begins execution.
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71 The boot code switches into RAM mode, and copies the entire section to
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72 $F000 and jumps to $F04F.
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73 </para>
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74 </section>
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75 </article>
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