ocr: THE SERIAL BUS (Continued) The Standard (Slow) Serial Bus The slow serial bus uses the port lines of the 6526 at U4, C1A 2, to drive ATN, CLK and DATA. The operation is the same as that of the C64 and when in C64 mode, slow to fast interference is automatically removed. The Fast Serial Bus Inc order to talk as a fast talker, the Controller must be addressing a fast device. When addressing any device, the C128 sends a fast byte, toggling the SRO line eight times, with the ATN line low. If the device is a fast device, it will record the fact that a fast Controller accessed it and respond with a ...
