Editing Atari STE Troubleshooting Guide (section)

== Boot Sequence ==

The STE boot sequence is similar to the ST, with some additions:

# '''Power-on:''' PSU provides +5V and +12V. GST MCU holds the 68000 in reset.
# '''Reset release:''' CPU begins executing from TOS ROM space.
# '''TOS 2.06 RAM test:''' If running TOS 2.06, a full RAM test is performed at boot. This takes approximately 3 seconds and can be aborted by pressing any key. The screen remains white during this test. On TOS 1.62, the RAM test is briefer.
# '''GEM desktop or floppy boot:''' Same as ST.

'''STE-specific boot symptoms:'''
* '''White screen for ~3 seconds then desktop appears:''' Normal behaviour on TOS 2.06 (RAM test). Not a fault.
* '''White screen indefinitely:''' RAM fault, ROM fault, GST MCU failure. The additional ~3 seconds of RAM test on TOS 2.06 means users may mistake a slow boot for a hang — wait at least 30 seconds before diagnosing a fault.
* '''Intermittent boot (sometimes works, sometimes white screen):''' Reset circuit capacitor failure — see [[Atari STE General Maintenance#STE-Specific Reset Issue|STE General Maintenance — Reset Issue]].