Hello world and hello Texas from Database

Install VistA with something like Astronaut. Get to a Mumps prompt: choose item 3 if you are using VistA Commander.

MUMPS>write "hello world"
hello world
MUMPS>write "hello " write $P(^DIC(5,48,0),"^",1)
hello TEXAS

What the above hello TEXAS line does:

• Invokes the Mumps function $P[iece], which is similar to but not exactly like the substring command in many other languages.
• The ^ indicates that this is not a local variable; Mumps will look for a global stored on disk and visible to other users.
• The global DIC holds the File of Files, but ^DIC with the subscript 5 says to look in file 5 (The STATE File)
• The ^DIC(5, is followed by a 48, which means entry 48 in the STATE File.
• The ^DIC(5,48, is followed by 0 because the NAME Field is stored in node 0 and the first piece.
• Then $P uses the ^ in this case as a delimiter, and returns the first piece.
• Since ^DIC(5,48,0)="TEXAS^TX^48^^1^1", MUMPS writes "TEXAS".