After TashTalk sends an RTS frame, require that external line activity contain a flag in order for a collision to be detected. Previously, any activity on the line would be detected as a collision, including the sync pulse sent by some Macs including the Power Macintosh 6100; this was preventing CTS frames from such Macs from being acted on properly and fully inhibiting data transmissions. With this change, it is possible for TashTalk to begin a transmission between the sync pulse and the frame that follows it, causing a collision, but the case is recoverable and the risk is negligible.