HP 50g Graphing Calculator - Manual (Page 804)

Page B-6
The CMD function shows the most recent commands, the PRG function
activates the programming menus, the MTRW function activates the Matrix
Writer,
Left-shift „ functions of the calculator’s keyboard
The CMD function shows the most recent commands.
The PRG function activates the programming menus.
The MTRW function activates the Matrix Writer.
The MTH function activates a menu of mathematical function.
The DEL key is used to delete variables.