PSXLinux (also known as Runix) is a Linux kernel and development kit for the PlayStation (MIPS-NOMMU).
A cross compiler is required to make the kernel compatible for the PlayStations CPU.
Runix did supply some tools on their website to transfer files if one had obtained or built their own serial cable.
The filename was: psx-serial.0.9.7.tar.gz Due to Linux ELF format not supported by the PlayStation, conversion is required and a suggested path is to first convert the Linux kernel file to ECOFF, the NetYaroze native executable standard.
[3] From Beta1 on the Runix sources[4] support Multiple or single memorycards of the PlayStations default size or larger.