In floating point, yes you are entirely correct. But that old mainframe'd show you a thing or two about I/O.

I respectfully disagree. The only place they come close is a late 90's huge disk arrays, but random access to SSD arrays are amazing and once you start looking at things like L2 cache bandwidth old mainframes start looking anemic.

Edit: An 1980 IBM 3081 could access up to 32 megabytes of main memory. A 5400-series "Harpertown" can have 24 megabytes of cache. So Modern CPU cache memory vs Mainframe main memory is not an unfair comparison. But that's just overkill the real shocker is 3081 had less bandwidth to it's registers than many modern computers have to it's local network. (It was below 40MHz and consumed 23 kilowatts of power).

PS: Feel free to post some actual numbers.

Why do you keep comparing old mainframes to current tech? Why not compare current mainframes to current tech -- its like those people who try and compare the java of 1998 with the C of today (you know "jvm takes minutes to start, and has x, y and z gc issues...").

Mainframes from IBM are under constant revision and update, just like server tech.

Because they are still being used. People think they need to replace an old mainframe with a cluster but that's just not true. Also, large modern day mainframes have become distributed systems so while you may still need a cluster you are already using one.

PS: We live in an age of horrable custom software, sitting on a monstrous stack of terrible commodity software. If you spend a noticeable amount of time waiting on a modern computer system it's really just a software problem. (Wait you actually want to use XML?) But, often upgrading the hardware is really the best option.