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.  
+# 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)!
+And it is still [5th](https://www.top500.org/lists/2017/11/).  
+They call this a Cray XK7
+
+## 18,688 compute nodes each with:
+* 1 x 16-core 2.2GHz AMD Opteron 6274 (Interlagos) processor
+* 32 GB of RAM
+* 1 x NVidia Kepler K20 GPU
+* Gemini high-speed interconnect
+* Total: 299,008 CPU, 18688 Kepler GPU, 598 TB of memory. 
+
 ## 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. You can only run 50 aprun's that is 50 independent mpi applications in one job script.
+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 16.  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 the mpi mom processes and PBS scripts
+this complicates what PBS scripts can do. 
+* Max 50 aprun's per job.
+* Don't run processes that cause much load outside of aprun invocation.
 ### 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
 ```shell-session
-qsub -W depend=afterok:JOBID fourth_1.sh
+qsub -W depend=afterok:JOBID next_jobs_pbs.sh
 ```
 * _afterok_ if you need previous job to be successful
 * _afterany_ if you don't care