Trace records

Example trace records for the terminal communication task trace are described.

The entries in the first 2 bytes indicate the processing that the analyzer (DFSICIO0) has completed. The entries in the last 2 bytes indicate the processing that the device-dependent modules (DDMs) have completed. As new entries are added, existing entries shift to the left. When the 2-byte area fills, the oldest entry is overwritten by the next-oldest entry. Therefore, the right-most entry of each 2-byte portion of register 0 identifies the most recent analyzer or device-dependent module activity.

The following figure shows the format of a sample terminal communications task trace record.

Figure 1. Example of a terminal communication task trace entry
Graphic shows "Register 0 = 0645 0211" as example and defines "0645" as "Analyzer entries" and "0211" as "DDM entries."

The sample terminal communication task trace entry in the figure indicates that the analyzer entries are 6, 4, and 5; DDM entries are 2, 1, and 1. An analysis of this trace data would yield the flow information shown in the following table.

Table 1. Example processing flow for a terminal communication task trace entry
Entry point Trace ID Processing description
2 DDM2 A write interrupt occurred.
6 A06 A write completed successfully.
1 DDM1 Another buffer was required.
4 A04 Room in the buffer is allowed for another message segment. (GN was issued to the message queue.)
1 DDM1 This segment was placed in the buffer, filling it or an EOM was detected. Setup for the write operation was completed.
5 A05 An output operation was requested.