Primary keys that do not always return immediately, namely BWAIT, TAPE, TBA and GTT, can be distinguished from entries. Jumping to such a key may cause some or all of the side effects of the key to occur even though the jump appears not to have occurred. In effect, when the key senses that a jump is about to occur, it performs its side effects {which may include waiting for some event} and enters a special state. A jump to the key can only proceed in the special state; when it does, the return {of parameters saved when the side effects were performed} occurs immediately. {To use such a key intelligently, only one domain should be trying to jump to it at any one time and it should not change its mind about what it is doing. This is one reason that such keys are restricted.}

Device Access Control

Device I/O Key

Tymnet Varian Base Access

Tymnet Lemcom Base Access


Checkpoint Key

IPL key

Journalize Page Key {A key with which to "journalize a page"}