B744 Thrust Mode At Altitude Capture

[NSEU]

Scenario: 744 takes off without VNAV armed. At 1000', the A/P is engaged (in current TO mode). The aircraft reaches, say 5000' (MCP altitude).

Is there an automatic A/T mode change? e.g. SPD... or...
Does the A/T remain in HOLD or THR REF at ALT capture/hold (until, say, a flap limit is reached or does it overspeed?)

Thanks.
Rgds.
NSEU