Old D&D and D&D3E/4E treat initiative and combat order differently like so:
D&D 3.5 / 4E: All participants roll individual initiative, once only at the start of combat. Each player takes all of his combat options on his own turn. No morale rules.
Basic D&D / Labyrinth Lord: Each side declares its actions ahead of time, then rolls group initiative, at the start of each round. Each side, as a group, makes all their movement at once, then ranged, spells, and finally melee, before the next side gets their actions. Morale has monsters roll to flee when the first ally is killed and when half their number are killed.
How does the difference affect combat? What are the advantages and disadvantages of the oldschool system? Is combat faster or slower under the old system, or is it more or less difficult to keep everything in order?