The OS-9 Boot Process

- -The OS-9 Boot Process -COCO Computer -AlanDeKok - -

-aland@striker.ottawa.on.ca -

- - - - - 1 - Tue Apr 29 21:53:46 EDT 1997 - Last update - - - - -Typing 'DOS' at the DECB 'OK' prompt loads in track 34 off of the disk. - - Track 34 gets loaded into address $2600, and execution of code -starts at $2602. - - $2602 contains a BRA to the execution point of the REL module. - - REL copies the boot track ($2600 to $3800) to address $ED00, and jumps to -another routine inside of REL, at the new address. - - REL then jumps to OS9p1, which sets up system variables, the system -memory map, system call tables, IRQ & SWI setup, and calls BOOT. - - BOOT reads sector $000000 off of a disk, and finds out where the -OS9Boot file is. - - BOOT requests system memory for the size of OS9Boot, seeks to where -OS9Boot is, and loads it directly into RAM. - - It then returns to OS9p1, after setting up pointers in low memory to -the OS9Boot file. - - OS9p1 links to OS9p2, and executes it. - - OS9p2 sets up more system calls, links to the clock module, and -calls it. - - Clock sets up some more system calls, starts multitasking, and -returns to OS9p2. - - OS9p2 then does F$Chain of 'CC3Go'. This prints a start up banner, -and runs your 'startup' file through a shell. - -