Before revision: When there is only one Master, the System Controller is not needed, and SYSCLK can be generated by the Master board Technical notes Signal inputs must be Schmitt trigger Signal outputs must have a fanout of 20 Backplane can have up to 21 sockets Active bus-termination recommended (270R pull-up to 2.8V) 7400 series chips are often used to build custom control boards, directly connected to the STEbus.
After revision: Only one TTL load per bus line signal per board50mm maximum length of bus signal line PCB trace on any board 500 mm maximum length of bus signal line lengthWhen there is only one Master, the System Controller is not needed, and SYSCLK can be generated by the Master board Technical notes Signal inputs must be Schmitt trigger Signal outputs must have a fanout of 20 Backplane can have up to 21 sockets Active bus-termination recommended (270R pull-up to 2.8V) 7400 series chips are often used to build custom control boards, directly connected to the STEbus.