Mine

local function drop()
    turtle.turnRight()
    turtle.turnRight()
    turtle.drop()
    turtle.turnLeft()
    turtle.turnLeft()
end

while true do
    local slot = turtle.getSelectedSlot()
    local count = turtle.getItemCount(slot)

    if count == 64 then
        drop()
    end

    sleep()
    turtle.dig()
end