SPIE, STAE, and DDT

If you are going to use DDT, you had better do NOSPIE under PL/I.

We really ought to work out some way for the domain's DDT to turn off SPIE by conversing with the OS simulator or something.

OS and OS programs have a habit of abending, which is something which is not handled well yet in Gnosis.

The O.S. simulator has a somewhat inelegant failure mode at this time. If your program suddenly appears at an address above x'800000' that means the simulator crashed at that address. You cannot see the code in the simulator from the application program domain, so if you are interested you must dial into the simulator domain's DDT. When you get there the commands ";t" and "0800000,ossim;u" will establish the symbol table. "CESINL]
;x16;" will display the most recent trace entry, and "ABENDREG;x040" will display the simulators registers at the time of the interrupt. Hopefully, you will never have to do this.

The interrupt log contains a 16 byte header, followed by 16 byte entries. The first word in the header always points to the most recently created entry, while the second and third words of the header define the addresses of the first and last entries in the log buffer. The log wraps to the beginning after the last entry has been used, and overlays the first entry.

The first byte of each log entry defines the class of log event. The following classes are defined at this time:

00-02 - an exit was taken from the OS simulation domain to the user domain.
bytes 1-3 contain the address of the OS simulation caller which initiated the user exit.

bytes 4-7 contain the address in the user domain which was "branched" to.

bytes 8-15 contain the contents of registers 0 and 1 established for the exit routine in the user domain.

80-8f - a domain trap was processed by the os simulator.
bytes 0-3 contain the abridged trap code generated by the kernel.

bytes 4-7 contain the application program domains PSW at the time fo the interrupt.

bytes 8-15 contain the application programs registers 0 and 1 at the time of the interrupt.

F0 - an entry was allocated, but not used as a regular log entry. This occurs when an interrupt was received which was not processed by the os simulator, or if an entry was made to the OS simulator with a nonzero databyte. Nonzero databytes are used to implement the synthetic domain keeper, meter keeper, and internal filedef functions, as well as to pass keys between the OS simulation domain and the application program domain.
if bytes 1-3 contain x'F0F0F0' the entry resulted from a "false" entry.

F0F0F0F0 - (in bytes 0-3) indicates a log entry was allocated, but not used. This will occur if a domain trap happens which the OS simulator chooses not to handle.