If I understand you need to insert into a text the Yen currency not supported on many keyboard layouts. You can retrieve it from the Symbol Table, a tool you can find by Start/Programs/Tools/System Utilities though its location may be different according Windows version.
you got that symbol by pressing ALT+157 because Notepad uses ANSI code NOT ASCII as all Windows applications do. ANSI and ASCII symbols are the same for codes between 00 - 127 but differ for the extended page (page 2 of the codepage). I live in Italy and writing an italian text in a DOS editor (e.g. la qualità è indispensabile), that can't be displayed correctly by Notepad. ASCII is for console mode and DOS applications only.
The information on Computing.Net is the opinions of its users. Such
opinions may not be accurate and they are to be used at your own risk.
Computing.Net cannot verify the validity of the statements made on this
site. Computing.Net and Purch hereby disclaim all responsibility
and liability for the content of Computing.Net and its accuracy.