I/O Processor Microcode Trace Facility
Original Publication Date: 1986-Aug-01
Included in the Prior Art Database: 2005-Mar-09
An input/output processor (IOP) microcode trace facility uses a simulated spooler and existing host trace facility to provide an on-line trace facility while preserving the real-time environment (no breakpoints or instruction stepping which would suspend the operation of code). The trace facility collects trace data needed to understand the internal workings of the microcode in such a way as to simulate a spooler. It then utilizes an existent trace facility running on the host processor to present the data in a desirable format to the end user. As shown in Fig. 1, the IOP internal microcode trace facility relies on preset trace points (defined by the microcoder) which are compiled into the microcode.