What a great episode!! Cameron’s enthusiasm, modesty, and perspective are awesome. Whether it’s open-source, mainframes, or inspiring folks to get started or change direction in tech, this guy is obviously something special. We need more like him in this world or perhaps we just need to be more intentional about encountering them. Thank you all for your efforts.

This was very interesting… I’m currently a retired “corporate IT guy” and started my career back in 1979 after learning COBOL at a for profit outfit named the “Computer Processing Institute” in Hartford CT.

COBOL actually is an acronym for COmmon Business Oriented Language, and I spent the first ten or twelve years of my career as a coder for banks and insurance companies, which all employed huge IBM mainframe installations to process their business.

There is one aspect of the business world of computing that was glossed over a bit as one of the points discussed was around the “two or three” key people who understand the topology of how the systems process the business. The key thing to understand about why this is the case is that the business no longer understands the intricacies of their own business, primarily because it resides IN THE CODE. The primary reason why various conversions to newer technology fail (aside from the fundamental difference between mainframe sequential and PC/server parallel based architectures) is that no one in the business can no longer describe accurately and completely how the business operates at the transaction level. This is the primary reason why there are thirty and forty year old applications chugging away on mainframes!

Loved this. At the end of the year, I won’t be surprised if it’s my favorite.

I was so excited for this discussion and even shared it with a few COBOL devs before listening myself.

This discussion fell short in almost every area except historical context.

The transactional processing strength of mainframes was an interesting point but completely overshadowed by failing to go deep on why and how. Contradictions throughout such as the number of COBOL devs is not a big concern at the moment to the IRS wants 600 by yesterday - what? The discussion felt completely off rails by the time I made it to the “How do we get people interested?” chapters.

The state of education is concerning given the important of mainframes to our economy.

Are comments being filtered?

This is a fantastic episode! Really enjoyed listening it and it’s been my favourite so far.

But it glossed over SO MUCH. I have so many more questions about mainframes by the end of the podcast than I had before.

• If single threaded performance is the core strength of mainframes, how does it compare to modern x64 CPU? Top x64 performer is roughly as fast as mainframe 1,3,5 or 10 years ago? Lets say it is 10 years, does it mean that modern x64 server could be used in place of mainframe if sent back in time or there is something more to it than just transactional speed?
• x64 CPUs don’t waste cycles, they wait on memory. Feeding ALU is biggest challenge, hence all those tricks with SMT, speculative execution, cache hierarchy. If system Z “doesn’t waste cycles”, how do they achieve it from architectural points of view? Enormous caches? low latency RAM? How does IPC compare between x64 and maintframes for a typical workload?
• On scaling vertically. It was mentioned that adding new processor or entirely new unit “to double performance” is an optional. Neither can help single threaded performance, so how does it scale actually? Or it can actually help single threaded performance with some insane hardware magic?
• If single threaded performance is the reason to go with mainframe, then why IBM invested in developing best in world hypervysor for zOS? More I think about it, less I understand.
• “main CPU just do transactions, everything else is offloaded to other subsystems”. How exactly does it work? x86 CPU doesn’t write bytes into ethernet either, network card does, often offloading big chunks like TCP stack. How mainframes are different? What are abstractions main CPU is operating with? Does it even pull data like in x86 or data and instructions being fed to the main CPU for completely deterministic and entirely local computation?
• With new model every 2 years, what were the biggest changes (other than raw speed) in a last decades?

I really hope there will be more podcasts on this topic.