How can a DEC VMS tape be read by an IBM mainframe?

At its peak in the late 1980s, Digital was the second-largest computer company in the world, with over 100,000 employees. It was during this time that they appeared to gain a feeling of invincibility, and branched out into software, producing products for almost every then "hot" niche. This included their own networking system, DECnet, file and print sharing, relational database, and even transaction processing. Although many of these products were well designed, most of them were DEC-only or DEC-centric, and customers frequently ignored them and used third party products instead. This problem was further magnified by Olsen's aversion to traditional advertising and his belief that well-engineered products would sell themselves. Hundreds of millions of dollars were spent on these projects, at the same time that workstations based on RISC architecture were starting to approach the VAX in performance. Constrained by their huge success of the VAX/VMS products, which followed the proprietary model, the company was very late to respond to commodity hardware in the form of Intel-based personal computers and standards-based software such as Unix and Internet protocols such as TCP/IP. In the early 1990s DEC found its sales faltering, and its first layoffs followed. The company that created the minicomputer and arguably the first computers for personal use did not effectively respond to the significant restructuring of the computer industry.