Format of CP's Trace Table Entries Under XA
            (Both XA/SF 2 and XA/SP 1)
   (Taken from the VM/SF CP Diagnosis Reference)
 
 
* The address of the next trace table entry is kept in Control Reg. 12.
 
* Each entry is 32 (x'20') bytes long (8 words).
 
* The first 3 words are formed by hardware by the TRACE instruction.
  They are x'7400', the low order 6 bytes of the TOD clock,
  x'0000', and a 2-byte Trace ID field (AKA the code).
 
* The last 5 words are the specified consecutive registers (Rn - Rn+4).
  The contents of these last 5 words is dependent on the Trace ID.
 
  Interesting trace table entries are
 
       |    |           |           |           |           |           |
 Type  |Code|0C|0D|0E|0F|10|11|12|13|14|15|16|17|18|19|1A|1B|1C|1D|1E|1F|
-------|----|-----------|-----------|-----------|-----------|-----------|
I/O Int|0500| Device @  | RDEVBLK @ |           |      I/O Old PSW      |
-------|----|-----------|-----------|-----------|-----------|-----------|
Runuser|0A00| 00000000  |  C'RUN'   | VMBLOCK @ |     VM Guest PSW      |
-------|----|-----------|-----------|-----------|-----------|-----------|
VIO Int|0C00|   User I/O Old PSW    | Device @  | Subchnl ID|           |
-------|----|-----------|-----------|-----------|-----------|-----------|
V. CSW |0D00|Virt. Inst.| Device @  |           |     Virtual CSW       |
-------|----|-----------|-----------|-----------|-----------|-----------|
V. SIO |0D90|Virt. Inst.| Device @  |    CAW    | First CCW in CCW Prog |
-------|----|-----------|-----------|-----------|-----------|-----------|
V. SIOF|0D91|Virt. Inst.| Device @  |    CAW    | First CCW in CCW Prog |
-------|----|-----------|-----------|-----------|-----------|-----------|
Sense  |10F0| Device @  |   The first 16 bytes of sense information.    |
-------|----|-----------|-----------|-----------|-----------|-----------|
Unit Ck|1C01| Device @  |           |           |     Failing CCW       |
-------|----|-----------|-----------|-----------|-----------|-----------|
Unit Ex|1C02| Device @  |           |           |     Failing CCW       |
-------|----|-----------|-----------|-----------|-----------|-----------|
To DSP |3600|           |           |           |           |           |
-------|----|-----------|-----------|-----------|-----------|-----------|