The original PL707 saved projects with extensions like .GRA (Grafcet), .LAN (Ladder), and .SYM (Symbols). These are binary files. If they have been copied via FAT32 or NTFS without proper binary mode (e.g., saved as text by accident), they are unrecoverable. Always use WinImage or raw dd to copy floppy disks.
Your original program uses memory overlays or an extended memory manager (EMM386). In DOSBox or a VM, you need to adjust the memory configuration. Old PL707 uses "Conventional Memory" (first 640KB). Load HIMEM.SYS and EMM386.EXE with the RAM parameter. telemecanique tsx 17 programming software
Before PCs were standard, Telemecanique sold dedicated handheld programming consoles. The original PL707 saved projects with extensions like