This 12 disk set contains the sources for CCP/M v. 3.1 from 1984 (including IBM PC & CompuPro XIOS). 

/Readme.txt

Source code files for Concurrent CP/M v3.1 (1984).

D1 - Kernel.
D2 - Kernel.
D3 - Kernel.
D4 - IBM PC XIOS.
D5 - CompuPro XIOS.
D6 - Utilities.
D7 - Utilities.
D8 - Utilities, IBM PC Boot.
D9 Utilities, RSP's.
D10 - Utilities, CompuPro Boot.
D11 - ASM-86.
D12 - ASM-86.