I think I know when my system screws up all the binaries (likely the
shared libraries, maybe related to mmap): I run Xemacs 19.13.
(pointing it at my SunOS system)

  After a bit, I thought it might be due to running compiles from
within Emacs, but that isn't the case, I hadn't run anything I get
things like:

amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 32 >config AMATERASU
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 33 >t  
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 34 >ls
AMATERASU       GENERIC         RAMDISK         files.sun3
AMATERASU~      GENERIC~        SMD_TEST        more.core
DISKLESS        Makefile.sun3   config.core     std.sun3
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 35 >config AMATERASU
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 36 >!!
config AMATERASU
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 37 >t 
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 38 >ls -lta
total 192
-rw-------  1 mcr  wheel  24860 Mar 26 03:04 more.core
-rw-------  1 mcr  wheel  33064 Mar 26 03:04 config.core
-rw-r--r--  1 mcr  wheel   3859 Mar 26 03:04 AMATERASU
drwxr-xr-x  2 mcr  wheel    512 Mar 26 03:04 ./
-rw-r--r--  1 mcr  wheel   3836 Mar 26 03:02 GENERIC
drwxr-xr-x  8 mcr  wheel    512 Mar 25 07:35 ../
-rw-r--r--  1 mcr  wheel   4322 Mar 18 07:28 files.sun3
-rw-r--r--  1 mcr  wheel   3893 Mar 12 04:33 AMATERASU~
-rw-r--r--  1 mcr  wheel   4465 Mar  1 07:23 Makefile.sun3
-rw-r--r--  1 mcr  wheel   3869 Feb 22 07:41 GENERIC~
-rw-r--r--  1 mcr  wheel    951 Jan 26 07:29 std.sun3
-rw-r--r--  1 mcr  wheel   2808 Dec 11 15:38 RAMDISK
-rw-r--r--  1 mcr  wheel   2747 Dec 11 15:38 DISKLESS
-rw-r--r--  1 mcr  wheel   2170 Oct 31 07:34 SMD_TEST
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 39 >t
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 40 >more AMATERASU
Illegal instruction (core dumped)
amaterasu-[/w/netbsd/src/sys/arch/sun3/conf] 41 >

 (t is an alias for 'ls -ltgaF | more')

  A reboot solves this problem.

  My system has otherwise been running very well with *this*
particular set of 8Mb of SIMMs. They are all newer SIMMs I note. 3/60s
are supposed to be happy with anything faster than 100ns. The older
(deeper, Sun original) SIMMs are 100ns. The newer ones are 80ns or
70ns ones that were probably bought more recently. 

   :!mcr!:            |  "Elegant and extremely rapid for calculation are the 
   Michael Richardson | techniques of Young tableaux. They also have the merit
                      | of being fun to play with." - p.47 Intro to Quarks&Partons
 Home: mcr@sandelman.ocunix.on.ca. PGP key available.