OLCF.md

 # TITAN -- It's a tricky beast, but it was [1st](https://www.top500.org/lists/2012/11/) (on the [top 500](https://www.top500.org/lists/2017/11/))!
 And it is still 5th.  
-## AMD Interlagos based machine, like OIC phase 5.
+## Differences from the standard Intel Linux Cluster
+### AMD Interlagos based machine, like OIC phase 5.
 The key is there are only one floating point unit per two cores.  So from a science perspective there are only 8 cores per node, not the sixteen listed.  Additionally your code needs to bind to just one core per pair.  See [Cray XK7 CPU info](https://www.olcf.ornl.gov/support/system-user-guides/titan-user-guide/#333)
-## Service nodes run mpimom processes and PBS scripts -- (this complicates what PBS scripts can do)
-## There is only one GPU per node, i.e. 16 CPU, 8 FPU, 1 GPU. It's generally on you to manage this.
+### Service nodes run mpimom processes and PBS scripts
+this complicates what PBS scripts can do. You can only run 50 aprun's that is 50 independent mpi applications in one job script.
+### There is only one GPU per node, so 16 CPU, 8 FPU, 1 GPU. 
+It's generally on you to manage this.
 
 # Qsub chaining jobs
-qsub -W depend=afterok:$JOBID fourth_1.sh
+```shell-session
+qsub -W depend=afterok:JOBID fourth_1.sh
+```
+* _afterok_ if you need previous job to be successful
+* _afterany_ if you don't care
 
 
-If you are having trouble, and there is not an example in the repo, it's probably best to just contact slack/here @epd [email](mailto:doakpw@ornl.gov)
+If you are having trouble, and there is not an example in the repo, it's probably best to just contact slack/here @epd or [email](mailto:doakpw@ornl.gov)
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