OS2LDR is the OS/2 kernel real mode initialisation and loader. It
resides in the root directory of the boot drive, and typically has
the SHR (System, Hidden, Readonly) attributes set. These attributes
have to be cleared (attrib -r -h -s c:\os2ldr) before the file can
be replaced.

In this ZIP file are 2 versions of OS2LDR - a debug and a retail
version. They are both built at the same code level (OS/2 2.0 ship
level plus fixes), but the debug version has additional code to
dump ASCII text out of the COM port at system boot time (9600 baud
N-8-1). COM2 will be used if it can be found, otherwise COM1. This
debug ASCII text output should be captured by an ASCII terminal
emulator on the com port for analysis. The retail version is called
OS2LDR on this diskette. The debug version is called OS2LDRD, and
needs to be renamed to OS2LDR to be used.