Editing Acorn Archimedes A3010 Troubleshooting Guide (section)

== Normal power-on sequence ==

A healthy A3010 runs a short power-on self test (POST) before booting RISC OS, stepping the screen border through a colour sequence and flashing any fault on the '''floppy-drive LED'''.<ref name="sm" /> The sequence tells you how far the machine gets:

# Border '''purple''': brief ROM and RAM test, IOC and VIDC initialised.
# Border '''blue''': extended memory test (up to about 12 s, depending on RAM).
# Border '''purple''': ARM3-present test (a standard A3010 has none).
# '''Black''' with a memory-size message, then RISC OS boots.

A '''soft reset''' (the Reset key) skips POST and starts RISC OS immediately; a '''power-on reset''' runs the full POST. A machine that boots from the Reset key but not from cold points to the power-on-reset circuit or a marginal PSU.<ref name="sm" />

On a VGA or multisync monitor the picture may be unsynchronised during POST because the test uses a 15 kHz mode; this alone is not a fault.<ref name="sm" />