The Programmer's Guide to TRSDOS Version 6 - Tim Mann's Home ...

7.6.31 @FLAGS$ SVC-101
This SVC will return a pointer to the base of the flags table. The pointer is returned in
register IY. The flag table is a table of 26 flags lettered A-Z. Certain additional
system variables are indexed relative to this pointer. Once the pointer is obtained, each
flag may be referenced relative to IY. For instance, if the SFLAG$ is needed, use
"IY+'S'-'A'" to reference the storage address of the flag. The following presents the
flag assignments available to the programmer:
Registers Affected: AF, IY.
Exit:
IY Returns the pointer to the base of the flag table.
AFLAG$
This "allocation" flag contains the starting cylinder number that is used by the
system's file space allocation routine when searching for free space on disk
media. The system defaults this value to cylinder 1.
CFLAG$
Bit 0 If set, then the system will not permit the change of HIGH$ via SVC-100.
This flag is reset by @EXIT and @CMNDI. This function is useful for
applications invoking system resources via @CMNDR while still wanting
control of the entire memory region through HIGH$.
Bit 1 If set, @CMNDR is executing. This flag is reset by @EXIT and @CMNDI. Note
that once an @CMNDR invocation is performed, the flag cannot be reset by the
system until "exit" of the application has been made via @EXIT or @CMNDI.
Bit 2 If set, it indicates that the command interpreter in SYS1 is requesting the
line input from the keyboard. This condition is important for keyboard
filters that may change the resident system overlay. If SYS1 is resident and
overwritten when bit-2 is set, you will crash the DOS upon passing control
back to the keyboard driver unless SYS1 is restored.
Bit 3 If set, then the system is requesting execution from either the "SET" or
"SYSTEM (DRIVER=" commands. This bit should be tested by drivers or filters
upon installation to ensure that they are being installed by the proper
system command rather than just by RUN or execution.
Bit 4 If set, then the @CMNDR SVC will only execute system LIB commands. Bear in
mind that "RUN" will be invokable which could then be used to override the
limitation.
Bit 5 If set, the SYSGEN library command will be inhibited. This may be useful to
inhibit application environments from altering the boot initialization
configuration.
Bit 6 If set, then @ERROR will not display any error message. This can be used to
inhibit the posting of error messages by programs invoked from @CMNDR.
Bit 7 If set, then @ERROR will pass the error message to the buffer pointed to by
register pair DE. See @ERROR for more data.
DFLAG$
Bit 0 Set to "1" if SPOOL is active
Bit 1 Set to "1" if TYPE AHEAD is to be active. Type-ahead can betoggled on/off
via this bit.
Bit 2 If set, it indicates VERIFY (ON) has been set.
Bit 3 If set, it indicates that SYSTEM (SMOOTH) is active.
Bit 4 If set, then MemDisk is active.
7-20