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/// Amiga Tip of the Week
by Robert Niles (with special thanks to Matt Schultz)
Alot of you have wondered why the Amiga displays those grey screens
upon it's start up, or you may have seen from time to time, the
computer lock up and there's a red screen staring you in the face.
Or have you ever heard that so-and-so's computer wouldn't work and
the caps-lock key kept flashing?
Well it's doing this for a reason...and it's trying to let you know
about it. Thanks to the informative posting on FidoNet's Amiga
Technical Echo by Matt Schultz, he simply, and in lay-man's terms
provides an outline of the process that the Amiga goes through during
it's start-up procedure. His message is below (edited for clarity):
I captured this message a few months ago. You may want to print it
out. I keep a copy in my wallet. :-)
Amiga system test is a complicated set of routines which it must go
through before you can do any work on it. During the system test the
Amiga is attempting to let you know if the system is well. Here is a
list of the start-up activities:
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. Begining 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, and or 68881.
20. Check to see if thee is an exception ...processor error
21. If so do a system reset.
During this system test the Amgia 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 meany 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 intialization test have passed.
If something is wrong with your system, you may see the following:
RED : If an 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
peformed 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 selftest.
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
If you are having problems with the Amiga, perhaps these codes will
help you and your repairman. This article was first authored by
Roy Frisque and published on the newsletter Scanlines. Roy obtain
his information from the Amiga Transactor.