There is the popular RPG Maker for PSOne that I know of, but for PC, there's RPG Maker VX and XP, but I don't know if they suit what you're looking for. A search result on http://www.gamfaqs.com
brought the PC versions up, which I didn't even know existed, so I'm sure you'll have a hard time finding them. The RPG Maker for PSOne matches perfectly what you're looking for and as you should know already, can be played on the PS2 and PS3 systems as well, if you have either of those.
The PS2 also has two version but I'm sure the graphics are above 16-bit era relevance.