Seattle, WA, USA

posted Fri Sep 08, 2017 10:18 pm

When you boot up your Amiga you are always greeted with a series of flashing screen colors. On most days the screen will change from dark gray to a couple lighter shades then white before marching on. On bad days, it flicks over to an actual color of the rainbow, each with its own heart-stopping meaning.

What do those colors mean? And what is the Amiga doing during the boot-up process in the first place?

The following is a collection of ancient and excellent information compiled from various sources.

During boot-up, the Amiga is going through a series of system checks and routines.
  1. Clear all chips of old data
  2. Disable DMA and interrupts during the test.
  3. Clear the screen.
  4. Check the hardware ....checks to see if 68000 is functioning.
  5. Change screen color.
  6. Do a checksum test on all ROMS.
  7. Change screen color.
  8. Beginning of system startup.
  9. Check RAM at $C0000 and move SYSBASE there
  10. Test All CHIP RAM.
  11. Change screen color.
  12. Check that software is coming in ok.
  13. Change screen color.
  14. Setup CHIP RAM to receive data.
  15. Link the libraries
  16. Check for additional memory and link it
  17. Turn the DMA and interrupts back on.
  18. Start a default task.
  19. Check for 68010, 68020, 68881 or other processor upgrades.
  20. Check to see if there is an exception or processor error
  21. If so do a system reset. 

During this system test the Amiga is sending vital information to the
screen with colors. If the system checks out ok, you will see the following
sequence that you have seen so many times.
DARK GRAY:  The initial hardware tested OK. the 68000 is running and the registers are readable.
LIGHT GRAY: The software is coming in and seems OK.
WHITE: The initialization test have passed.

The failure mode screen colors:
  • Turquoise (0x0CC) (A1000 only): RAM failure in the Kickstart WCS
  • Green (0x0F0) error in the lowest 256 bytes of Chip RAM. Possible causes, defective CIA-A IC or defective Agnus IC.
  • Yellow (0xFE5) an unexpected processor exception before the appropriate system failure message was prepared. This could mean defective hardware or an attempt to access a RAM address where no RAM exists.
  • Red (0xF00) invalid KickStart ROM checksum.
  • Magenta (0xF0F) single-task or cold-start initialization failed.
Another listing of screen color interpretations:

RED Kickstart ROM error Two ICs in A1200, A3000, A4000
BLUE Custom chip problem Denise Paula Agnus
YELLOW Above problems combined
LIGHT GREEN CIA (U7/U300) problem
BLACK CIA (U7/U300) problem If not booting
DARK GRAY Hardware tested OK
LIGHT GRAY Software tested OK
LIGHT GRAY CIA (U8/U301) problem Stops at gray, CIA defective
No video R406 or R215 open R406=1 ohm R215=4.7 ohm
Video scrambled Agnus or Denise defective

If the Amiga caps lock key LED blinks repeatedly at boot up, another series of error messages must be consulted:
  • One blink: keyboard ROM checksum error
  • Two blinks: RAM failure
  • Three blinks: watchdog timer failure
If something is wrong with your system, you may see the following:
  • RED: Error was found in ROMS.
  • GREEN: Error found in the CHIP RAM.
  • BLUE: Error was found in the custom chips.
  • YELLOW: If 68000 found an error before the error trapping software (GURU) was running.
 The Keyboard has it's own processor, RAM and ROM. A selftest is performed
on power-up in the following sequence.
  1. Performs checksum on ROM's
  2. Checks 64 bytes of RAM.
  3. The timer is tested.
  4. Performs handshake with computer and gives results of self-test.
If the keyboard does not pass the test it will notify you that it is not
working properly. This information is indicated with the blinking of the
CAPS-LOCK light.
  • One Blink:    Keyboard ROM check failed.
  • Two Blinks:   Keyboard RAM checked failed.
  • Three Blinks: Watch dog timer failed
  • Four Blinks:  A short between two row lines or special control keys.