Exchange Traded Options are traded on the Derivatives Trading Facility, which is a separate computer system. Initially, only a few stocks were traded this way to enable the marketplace to adjust to the new trading method. Brokers may use other systems for trading. Best priced orders have priority. If there is more than one order at the same price, the order that was placed first takes precedence.
Large orders have no priority over small orders.
The ticker moves across the top of the screen and shows trades as they occur. The All Ordinaries Index shows every 30 seconds. Many on-line brokers also have a ticker on their web site. Watch is a stock summary. Details update as the market changes.