diff --git a/README.md b/README.md
index b71f859c..a8211dfd 100644
--- a/README.md
+++ b/README.md
@@ -37,5 +37,6 @@ from scratch.
    - PDSET, set time and date.
    - KSFEDR, manipulate front-end file system.
    - LOCK, shut down system.
+   - ATSIGN DEVICE, load device drivers.
 
 4. Finally, the whole file system is dumped to tape.
diff --git a/build/build.tcl b/build/build.tcl
index 700bc0b4..928363ba 100644
--- a/build/build.tcl
+++ b/build/build.tcl
@@ -145,6 +145,11 @@ expect ":KILL"
 respond "*" ":delete sys;ts lock\r"
 respond "*" ":link sys;ts lock,sysbin;lock bin\r"
 
+respond "*" ":midas sysbin;_syseng;@dev\r"
+expect ":KILL"
+respond "*" ":delete sys;atsign device\r"
+respond "*" ":link sys;atsign device,sysbin;@dev bin\r"
+
 respond "*" "\005"
 respond "sim>" "at tu0 out/output.tape\r"
 respond "sim>" "c\r"