43     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           44     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           45     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           46     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           47     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           48     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           49     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           4f     | 00 | 00 | 08 | 00 | 0 0 0 0 0 0 0 0 |                  50     | 00 | 00 | 09 | 00 | 0 0 0 0 0 0 0 0 |                  51     | 00 | 04 | 03 | 03 | 0 0 0 0 0 4 1 3 | _getdents        52     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           53     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           54     | 00 | 00 | 0a | 00 | 0 0 0 0 0 0 0 0 |                  55     | 00 | 06 | 04 | 03 | 0 0 0 0 3 1 1 3 | _getmsg          56     | 00 | 06 | 04 | 03 | 0 0 0 0 3 1 1 3 | _putmsg          57     | 00 | 05 | 03 | 03 | 0 0 0 0 0 3 5 1 | _poll            58     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           59     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           5f     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           60     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           61     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           62     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           63     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys           64     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys    65     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          66     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          67     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          68     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          69     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          6f     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          70     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          71     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          72     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          73     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          74     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          75     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          76     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          77     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          78     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          79     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7d     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7e     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys          7f     | 00 | 05 | 05 | 0a | 0 0 0 0 0 0 0 0 | _clocal     _v7sysent:    00     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |    01     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _ftime       02     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       03     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nullsys     04     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       05     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       06     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       07     | 00 | 05 | 05 | 0a | 0 0 0 0 0 0 0 0 | _clocal      08     | 00 | 00 | 00 | 08 | 0 0 0 0 0 0 0 0 | _cxenix      09     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       0a     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       0b     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       _s3sysent:    01     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |    02     | 00 | 06 | 04 | 03 | 0 0 0 0 3 3 1 1 | _statfs       03     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _fstatfs      04     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _setpgrp      05     | 00 | 00 | 00 | 08 | 0 0 0 0 0 0 0 0 | _cxenix       06     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _uadmin       07     | 00 | 00 | 00 | 09 | 0 0 0 0 0 0 0 0 | _utssys       08     | 00 | 03 | 03 | 03 | 0 0 0 0 0 3 3 3 | _fcntl        09     | 00 | 03 | 02 | 05 | 0 0 0 0 0 0 5 3 | _ulimit       0a     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 1 | _rmdir        0b     | 00 | 00 | 02 | 03 | 0 0 0 0 0 0 3 1 | _mkdir        0c     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys        _svidsysent:    01     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 |    02     | 00 | 06 | 04 | 03 | 0 0 0 0 3 3 1 1 | _statfs      03     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _fstatfs     04     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 3 | _setpgrp     05     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys       06     | 00 | 00 | 03 | 03 | 0 0 0 0 0 1 3 3 | _uadmin      07     | 00 | 00 | 00 | 09 | 0 0 0 0 0 0 0 0 | _utssys      08     | 00 | 00 | 03 | 03 | 0 0 0 0 0 3 3 3 | _fcntl       09     | 00 | 00 | 02 | 05 | 0 0 0 0 0 0 5 3 | _ulimit      0a     | 00 | 00 | 01 | 03 | 0 0 0 0 0 0 0 1 | _rmdir       0b     | 00 | 00 | 02 | 03 | 0 0 0 0 0 0 3 1 | _mkdir       0c     | 00 | 00 | 03 | 03 | 0 0 0 0 0 0 0 0 | _nosys   _clentry: used for oem CLOCAL routines.  Empty on my system._cxentry: used for SCO added stuff.    00     | 00 | 05 | 03 | 03 | 0 0 0 0 0 4 7 1 | _shutdown    01     | 00 | 04 | 03 | 03 | 0 0 0 0 0 7 3 3 | _locking    02     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 1 | _creatsem    03     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _opensem    04     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _sigsem    05     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _waitsem    06     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _nbwaitsem    07     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 3 | _rdchk    08     | 00 | 01 | 01 | 03 | 0 0 0 0 0 0 0 4 | _stkgrow    09     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys    0a     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 5 3 | _chsize    0b     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 1 | _ftime    0c     | 00 | 02 | 01 | 05 | 0 0 0 0 0 0 0 5 | _nap    0d     | 00 | 05 | 04 | 01 | 0 0 0 0 3 4 3 1 | _sdget    0e     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdfree    0f     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 7 | _sdenter    10     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdleave    11     | 00 | 02 | 01 | 03 | 0 0 0 0 0 0 0 7 | _sdgetv    12     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 7 | _sdwaitv    13     | 00 | 05 | 03 | 01 | 0 0 0 0 0 7 5 3 | _brkctl    14     | 00 | 00 | 00 | 00 | 0 0 0 0 0 0 0 0 | _nosys    15     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 1 3 | _nfs_sys    16     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _msgctl    17     | 00 | 03 | 02 | 03 | 0 0 0 0 0 0 3 5 | _msgget    18     | 00 | 05 | 04 | 03 | 0 0 0 0 3 3 1 3 | _msgsnd    19     | 06 | 07 | 05 | 03 | 0 0 0 3 5 3 1 3 | _msgrcv    1a     | 00 | 05 | 04 | 03 | 0 0 0 0 7 3 4 3 | _semctl    1b     | 00 | 04 | 03 | 03 | 0 0 0 0 0 3 3 5 | _semget    1c     | 00 | 04 | 03 | 03 | 0 0 0 0 0 4 1 3 | _semop    1d     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _shmctl    1e     | 00 | 04 | 03 | 03 | 0 0 0 0 0 3 4 5 | _shmget    1f     | 00 | 04 | 03 | 06 | 0 0 0 0 0 3 7 3 | _shmat    20     | 00 | 04 | 03 | 03 | 0 0 0 0 0 1 3 3 | _proctl    21     | 00 | 03 | 00 | 06 | 0 0 0 0 0 0 3 7 | _execseg    22     | 00 | 02 | 00 | 03 | 0 0 0 0 0 0 0 7 | _unexecseg    23     | 00 | 00 | 03 | 03 | 0 0 0 0 0 5 5 1 | _swapon    24     | 00 | 09 | 05 | 03 | 0 0 0 1 1 1 1 3 | _selectI couldn't really figure out how uadmin() was accessed.  libc'suadmin.o links in a routine that calls system call 0x37.  Hmmm...The _cxentry is accessed by (documented in the programmer's referenceunder System Calls) setting a bit in the system call number.  It seemsas though it actually shifts the system call number up half a word andputs 0x28 in the low order halfword.Now we see that select() exists as a cxenix function (number 0x24),There is also poll(), putmsg(), and getmsg() -- streams stuff.Since the tty device is not a streams device (actually it looks as ifthe streams stuff has been nulled out -- look at the master file formore information) it is highly unlikely that these routines will doanything useful.  Infact, they don't.  Change the SYSNUM (and symbols)in the example open.s above to their appropriate values to try out thestreams routines.select.s looks something like:; select;;;	title	select	.386SYSNUM	equ 	2428hextrn	_errno:dwordpublic  _select_TEXT	segment  dword use32 public 'CODE'	assume   cs: _TEXT_select	proc near	mov	eax, SYSNUM		; Get system call number.	;	; I don't even pretend to understand masm syntax.  I tried	; the following line (and variations) without any success.	;;	call    far 7:0			; Switch to kernel and call SYSNUM.	;	; Don't laugh, it works.	;	db 9ah	dw 0,0	dw 7	jb	short _cerror		; below == error.	xor	eax, eax		; zero return value (no error).	ret				; done._cerror:	mov	_errno, eax		; Save error code in _errno.	mov	eax, -1			; Return -1 (as error).	ret				; done._select	endp_TEXT	ends	endThere is a header file you'll need in <sys/select.h> which has someinformation in it.A Synopsis of the SCO XENIX implementation:	#include <sys/select.h>	nfds = select(width readfds, writefds, exceptfds, timeout)	int width, *readfds, *writefds, *exceptfds;	struct timeval *timeout;  /* timeval is a pointer to a structure */I tested select() and found it to be half way implemented.  It seemsas if there must be some extra field in struct cdevsw <sys/conf.h>.So, I guess I wait 'til 3.2.Pax, KeithPs, FYI.Pps, if I made a mistake in my description of system call handling onSCO XENIX or what not, please correct me.Ppps, `call far 7:0' seems really reasonable to me.-- ag@elgar.CTS.COM         Keith Gabryelski          ...!{ucsd, crash}!elgar!ag