Try downloading free Code Manager software from public downloads area of commbox.com.au. Although it is intended for use with our systems, it comes with a huge library that includes discretes, can read and write Pronto Hex and it allows you to easily create your own codes, given you know the hex or binary data. It stops you from making codes that would be illegal (i.e. not fit the format of the rest of the codes in the set) and there is a manual that contains collected wisdom on IR codes from IR code experience that dates back to the late 1970s!

The big difference with Code Manager is it displays IR codes as waveforms, allowing you to see exactly what is happening.

BTW, this software was originally written for CPM, then DOS, 16 bit Windows and now 32 bit Windows so that's how far back it goes!