Editing Amstrad CPC 664 Troubleshooting Guide (section)

== Power-On Behaviour ==

A healthy CPC 664 with firmware v2 (mask ROM IC103 part 40012 for the English-language model) and AMSDOS ROM (part 40015) goes through the following at power-on:

# +5 V and +12 V rails come up from the monitor through the DC cord.
# The Gate Array (IC116, 40010 / 40007) generates the Z80 reset pulse, the 4 MHz Z80 clock, and the 1 MHz CRTC and AY-3-8912 clocks.
# CRTC (IC108) generates HSYNC and VSYNC; the Gate Array generates the RGB output.
# The Z80 reads the OS+BASIC ROM (IC103) starting at address 0000h.
# AMSDOS ROM is initialised: a |&nbsp;DIR command tests the floppy controller; if successful, the system advertises disc support.
# The boot screen appears:
#: '''Amstrad 64K Microcomputer (v2)'''<br>"&copy; 1985 Amstrad Consumer Electronics plc<br>"and Locomotive Software Ltd."<br>"BASIC 1.1"<br>"Ready"
# The cursor appears.

For Schneider-branded units the first line reads "Schneider 64K Microcomputer (v2)".

If the disc drive is present but has a fault, the system may take longer to reach "Ready" because AMSDOS retries the drive initialisation several times before giving up. A 4&ndash;6 second delay between video and prompt is a clue that the drive is being polled but is not responding.