The STEbus is a high reliability computer bus, designed for industrial control, so the SCPC88 can operate in environments where the original PC cannot. A bus master (such as a processor board) can drive up to 20 peripheral slaves. All STEbus boards are in a single standard Eurocard size.
The STEbus is asynchronous, which means that the processor board must wait until the slave board responds. The SCPC88 processor board will timeout after a preset period and read whatever is on the data bus at that time. This makes the SCPC system compatible with the PC.
Presuming your SCPC system is working, then the processor board is successfully transferring data to and from the slave boards (the SPEGA, SPDC, and SPCOM) via the STEbus. In most development work, you will need other slaves for measuring or controlling the real world. You should take care that additional slaves are not located at IO addresses which conflict with devices already present in the SCPC system. See the 'I/O Devices' section for details on this.
The range of STEbus boards allow you to expand by adding all the usual features such as non-volatile RAM, EPROM, or EEPROM, a real-time clock, serial channels, and parallel printer ports. There is also a large range of control and measurement boards such as analogue and digital I/O, stepper and servo controllers, IEEE488 GPIB, and factory networking. For a fuller description of the range of STE boards consult the current catalogue.