Was recently looking at some of the Beagle Brothers tools and noted Double-Take. It has 2-way scroll. Nice for program listings and catalog pause and up down scrolling, among many other tools. Boot it’ control-F for prompt and select 1,2, or 3 for variations.
Note: this is version 2.1 which is ProDOS. This version is available on the Asimov and Internet archives. However, that file is a .po file. From it I made a .do file which will run in the Virtual ][ Emulator…which rejects most .po types including this one. If you need the .do version just Private Message me.