i think it is impossible to run WinAsm Studio under win 3.1. why 3.1 exactly? use win95. i've been using win95 with 486DLC-40 CPU, 8Mb RAM and 170Mb hdd (but there was no winasm studio yet that time). also, on slow systems you may notice sufficient delay on loading project by latest WinAsm Studio, up to 30 sec (P24-100MHz/32MbRAM/Win98) (but after loading works enough fast). for dos it is better to use dos editors like MultiEdit, embedded into DOS Navigator - they can save latest status, so, if your program will hang and you will reboot instead of switching into another window - your status in editor will be restored (open files and postitions there). from ME you may run programs with I/O redirection into child window, thus you can run or debug some code "directly from editor" (of course, you have to learn about its macros to do that). also, look at FASMD - it is an editor with embedded fasm for dos, at least, DN (now) and fasm are free.