IBM PC 5150 Information and Software
Released in 1981, the IBM PC 5150 is the first x86 Personal Computer ever released.
Downloads
--> MS-DOS 2.1 (not allowed to distribute, sorry)
--> Advanced Diagnostics 2.25
--> Diagnostics 2.05
--> Exploring Monochrome Displays
--> Exploring Colour Displays
--> 5150 Manuals
Manuals in the ZIP file include: BASIC, Guide to Operations, Hardware Maintenance Manual and Technical Reference.
Some of these files were downloaded from the ibm5150.com website before the owner removed the site and got rid of the 5150s.