
Table 
| Bits | Name | Meaning | 
| 
 | 
 | 
 | 
| 7:4 | PCSEL1 | Counter 1 event selection. PCSEL1 described in Table  | 
| 3:0 | PCSEL2 | Counter 2 event selection. PCSEL2 described in Table  | 
| 
 | 
 | 
 | 
Table 
| 
 | DIGITAL UNIX | 
| 
 | 
 | 
| Bits | Meaning | 
| 
 | 
 | 
| 63:31 | MBZ | 
| 30 | Stop count in user mode | 
| 29:10 | MBZ | 
| 9 | Stop count in PALmode | 
| 8 | Stop count in kernel mode | 
| 7:1 | MBZ | 
| 0 | Monitor selected processes (when clear monitor all processes) | 
| 
 | 
 | 
Setting any of the "NOT" bits causes the counters to not count when the processor is running in the specified mode. Under OpenVMS Alpha, "NOT_KERNEL" also stops the count in execu- tive and supervisor mode, except as noted below:
| NOT_BITS | Counters Operate Under These Modes When Bits Set: | |||||
| 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
| K | U | P | 
 | 
 | 
 | 
 | 
| 0 | 0 | 0 | K E S U P | |||
| 0 | 0 | 1 | K | E | S | U | 
| 0 | 1 | 0 | K | E | S | P | 
| 0 | 1 | 1 | K | E | S | 
 | 
| 1 | 0 | 0 | 
 | 
 | 
 | U P | 
| 1 | 0 | 1 | 
 | 
 | 
 | U | 
| 1 | 1 | 0 | 
 | 
 | 
 | P | 
| 1 | 1 | 1 | 
 | E | S | (here "NOT_KERNEL" stops kernel counter only) | 
| 
 | 
 | 
 | 
 | 
 | 
 | 
 | 
Note:
DIGITAL UNIX counts user mode by using the executive counter; that is, the count for executive mode is returned as the user mode count.
Waivers and 
