annotate bootrom.notes @ 4:a821df9c4457

boot ROM re: got as far as UART init
author Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
date Tue, 16 Apr 2013 05:36:59 +0000
parents e3f8fe6a848e
children a445735685ba
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3
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
1 RAM layout:
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
2
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
3 800000 7 words:
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
4 soft-vector pointers: by default the following 7 words at
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
5 80001C are filled with ldr-jump instructions, which read
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
6 from these 7 words and load them into PC
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
7 80001C 7 words:
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
8 hard vectors: the physical vector locations in the ROM
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
9 contain branch instructions to these 7 RAM addresses
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
10
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
11 800104: word initialized to 0x0001D4C0
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
12 800108: byte initialized to 0x01
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
13
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
14 800534: byte initialized to 0x00
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
15
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
16 8005C0: appears to be the intended low address (bottom) of the stack
e3f8fe6a848e boot ROM re: started on main() and the 0xe2c routine
Michael Spacefalcon <msokolov@ivan.Harhan.ORG>
parents:
diff changeset
17 80074C: top of the stack (initial value loaded into SP)