Added English Language description for stbup instruction

diff --git a/openpower/isa/pifixedstore.mdwn b/openpower/isa/pifixedstore.mdwn
index 1fe36aa6c65da2c00f271714b3473e73ad4b9bac..d3c2cf5f9844ce1d87f90289e5976db2dcaad1d2 100644 (file)
--- a/openpower/isa/pifixedstore.mdwn
+++ b/openpower/isa/pifixedstore.mdwn
@@ -16,6 +16,16 @@ Pseudo-code:
     MEM(ea, 1) <- (RS)[XLEN-8:XLEN-1]
     RA <- EA
 
+Description:
+
+    Let the effective address (EA) be the sum (RA)+ D.
+    (RS)[56:63] are stored into the byte in storage addressed
+    by EA. 
+
+    EA is placed into register RA.
+
+    If RA=0, the instruction form is invalid.
+
 Special Registers Altered:
 
     None