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Amiga 'Boot' Sequence

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                      Amiga 'Boot' Sequence

  After getting a number of inquiries from fellow Amiga users about what's
  wrong with their Amigas when their Caplock key starts flashing, or, why
  the screen flashed odd colors, I decided to create this file.

  The Amiga goes through a rather elaborate startup sequence which is a
  series of diagnostic tests the Amiga goes through during each 'cold' or
  'warm' boot. The following is a list of what happens during each and
  every 'boot':

  1. Clear all old data in RAM
  2. Disable DMA and interrupts
  3. Clear the screen
  4. Check hardware (is the 680x0 working?)
  5. Change screen color indicating pass/fail
  6. Perform checksum test of all ROMs
  7. Change screen color indicating pass/fail
  8. Begin system startup
  9. Check RAM at $C0000..move SYSBASE there
 10. Test CHIP RAM
 11. Change screen color indicating pass/fail
 12. Check if software is coming in OK
 13. Change screen color indicating pass/fail
 14. Set up CHIP RAM to receive data
 15. Link libraries
 16. Check for any additional RAM and link it
 17. Turn on DMA and interrupts
 18. Start default task
 19. Check processor and MMU type
 20. Check for an Exception (processor error)
 21. If found, do a reset
 22. If not, normal 'boot'

As these tests are running, the Capslock key will normally 'flash' once,
and the screen will cycle colors. The chart below used in conjunction
with the above steps indicates both a 'normal' and an 'abnormal' boot.

NORMAL                                 Fault Condition

Sreen color:
   Dark Grey                           Red (indicates error in ROM)
   Light Grey                          Green (error in CHIP RAM)
   White                               Blue (error in a Custom Chip)
                                       Yellow (680x0 found an error)

Capslock Key:
  Stays on for several secs            One blink (ROM checksum failed)
                                       Two blinks (RAM test failed)
                                       Three blinks (Whatchdog timer)
                                       Four blinks (A short exists between
                                                    2 lines or one of the
                                                    special keys)


Please note that the capslock 'blinks' are short in duration (about one
second) and that your screen colors may falsely indicate a problem when
you do a 'warm' boot depending on what state the Amiga was in before the
warm boot. Its best to watch for these diagostic errors upon initial
startup. If your Amiga exhibits any of these errors frequently, you should
take it to an Authorised Service Center for service. The most common
error you will encounter is that you'll see a bright green screen at the
initial boot..this usually indicates that an addon RAM board is not
seated in its socket properly. Try reseating it before you take it all to
your dealer. You may save yourself some money;)