I used to work with Digital Equipment Corporation (DEC) VAX systems and for fun built up a VMS 7.1 system using the amazing processor simulator SIMH to get a VAX8600 running. One of the challenges was lack of TCP/IP networking stack to push software backup savesets to the system. One process involves creating an ISO of local files then mounting that image inside SIMH and mounting it in VMS. Painful since it modifies the files and filenames.

That challenge led me to create the ods2v2 tool (github.com/allenpomeroy/ods2v2)

ods2v2

This is a from-scratch implementation of DEC Files-11 (ODS-2) utility to copy local files from a Linux (likely a Mac too) system to an ODS-2 disk volume that is usable by SIMH simulator running a VAX/VMS (vax8600) OpenVMS 7.1 system.

The ods2v2 utility can run a minimal set of VMS DCL type commands on the disk file, with the intent of transferring files into or out of the VMS system. Reads and writes real ODS-2 disk images – the same format real VMS’s own MOUNT, INITIALIZE, COPY, and DIRECTORY commands use. No VMS installation, SIMH emulator, or license required to use it.

Built directly from the Files-11 On-Disk Structure Specification, not from copying an existing implementation, and validated repeatedly against real OpenVMS 7.1 (via SIMH) throughout development with real MOUNT / DIR / TYPE / COPY and ANALYZE/DISK commands on a vax8600 running OpenVMS 7.1 in simh. Every significant bug this project found (a word-swapped 32-bit field, an inverted bitmap convention, directory records needing to be storage-sorted) was found with analysis on an OpenVMS system.