diff --git a/docs/expert/infrastructure/p5.md b/docs/expert/infrastructure/p5.md
index b82df87a3c7ec425397820f5fe783b6fd5e12679..7b6e1b9faeb79e91cda80be38d831364cdc26734 100644
--- a/docs/expert/infrastructure/p5.md
+++ b/docs/expert/infrastructure/p5.md
@@ -100,3 +100,23 @@ The notification polices can be changed by opening a [Jira ticket](https://its.c
 ### Fibers
 
 The complete DAQ fiber mapping can be found in [this document](fiber-mapping.txt).
+
+## Mainframes
+
+The CAEN mainframes used to handle the low-voltage and high-voltage systems are
+physically the responsibility of the TC group, while their controlling software
+is the responsibility of the DCS group. Nevertheless, the low-level system
+administration (e.g. networking, operating system maintenance,...) is taken
+care of by the Online Systems group.
+
+Below is a list of the maintained mainframes.
+
+| Hostname         | Location  | DCS Numbering | Comments                         |
+| ---------        | --------- | --------      | ---------                        |
+| `gem-lv-01`      | S4F02     | LV            |                                  |
+| `gem-hv-01`      | S1G12     | HV #01        | GE-1/1 near side (sectors 28-09) |
+| `gem-hv-02`      | S1G12     | HV #02        | GE-1/1 far side (sectors 10-27)  |
+| `gem-hv-03`      | S1F12     | HV #03        | GE+1/1 near side (sectors 28-09) |
+| `gem-hv-04`      | S1F12     | HV #04        | GE+1/1 far side (sectors 10-27)  |
+| `gem-ge21-hv-01` | S1F13     | HV #05        | GE+2/1 near side (sectors 15-05) |
+| `gem-ge21-hv-02` | S1G13     | HV #06        | GE-2/1 near side (sectors 15-05) |
diff --git a/docs/setups-description.md b/docs/setups-description.md
index 72fea24a1dc45b248b4952079fafcb2b07e88f52..8b6329d4cbe240ea782ee61dbf01bd397d32287f 100644
--- a/docs/setups-description.md
+++ b/docs/setups-description.md
@@ -147,8 +147,8 @@ an exercise left for the reader.
 
 Newer Linux releases (e.g. AlmaLinux 9) disable the old and insecure algorithms
 or protocols by default. While technically a good thing, this newer default
-prevents connecting to older nodes, such as SYx525 CAEN mainframes or non
-patched CTP7. In such cases, you get errors such as:
+prevents connecting to older nodes, such as non updated SYx525 CAEN mainframes
+or non patched CTP7. In such cases, you get errors such as:
 
 * `ssh_dispatch_run_fatal: Connection to ww.xx.yy.zz port 22: error in libcrypto`
 * `Unable to negotiate with ww.xx.yy.zz port 22: no matching host key type found. Their offer: ssh-dss`