Notes about the S1 file extension:
Incorrect file associations could be the result of underlying issues within your PC system. As such it is highly recommended to scan your PC for invalid registry entries, unused processes and other unfavourable system settings to identify slowdown issues.
The S1 file type is primarily associated with 'Free Pascal' by FPC Development Team. Free Pascal (aka FPK Pascal) is a 32 or 64 bit (from 1.9.6) pascal compiler. It is available for different processors Intel x86, Amd64/x86 64 (from 1.9.6), PowerPC (from 1.9.2), Sparc (from 1.9.6) and Motorola 680x0 (1.0.x only). The following operating systems are supported Linux, FreeBSD, NetBSD, MacOSX/Darwin, MacOS classic, DOS, Win32, OS/2, BeOS, SunOS (Solaris), QNX and Classic Amiga.