> I'm going to channel the efficient market hypothesis (I apologize) here and say that people have done that cost comparison and not one of them bought mainfram

> I'm going to channel the efficient market hypothesis (I apologize) here and say that people have done that cost comparison and not one of them bought mainframes. Heck, Google ported their entire monorepo to Power but not to z. Nah, there are a ton of businesses of all sizes across the world with many man-years of effort put into writing software that runs on various layers of the IBM stack from Cobol on up. For one regional grocery store I know of they started in the 70s. Let's average 10 developers on staff churning out 4GL, Cobol, and whatever else since 1979. I hear it runs webservices now to serve the desktop and mobile client apps. 10 engineers * 43 years = 430 man-years put into a pile of software highly customized to exactly how they do business, from corporate & accounting to the warehouses to the ice cream factory to the industrial-scale bakery to the retail stores. Every single process at the company driven by mountains of custom software. The thing that knows more people buy Texas Toast at Store #473 so it prompts the manager to order extra and the bakery to put an extra Texas Toast run into the already tight schedule? Yeah that runs on the IBM mainframe... because that's where the cash register sales data goes and where the managers handle orders and where warehouse tickets are printed and where the bakery solves the traveling salesman problem to create schedules around quickly expiring products (did I mention the delivery truck schedules also run on the mainframe?). If we assume it would "only" take 10% of the effort to replace, mythical man-month is not a problem, and you can handle dual-running the integrated systems for the decade it will take to perform the swap... you saved a year of your on-staff developer's salaries while putting every part of your business at risk of exploding (and ceasing all improvements to the existing stack lest you chase a moving target)... and you end up with something more or less equivalent except on commodity hardware. $1m for IBM hardware? $5m? $10m? Pfffffffttttt... Chump change. Where do I sign the check? Sold and sold. Don't even bother sending a rep out.