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"- The CPU in the node isn't important. The binary format for IBM mainframes is a virtual machine language and has to be just in time compiled on the node where
by ch_123 6y ago
"- The CPU in the node isn't important. The binary format for IBM mainframes is a virtual machine language and has to be just in time compiled on the node where it will run if a binary wasn't already cached from earlier transactions."
Maybe I am nitpicking, but this sounds more like the System/38 and AS/400 rather than the mainframe. Is the author referring to some particular technology which runs on top of the mainframe?
- monocasa 6y agoI've heard of true mainframe (ie. s/360, not that minicomputer nonsense that people call mainframes for some reason) systems that'll compile the code to run just in time on the equivalent of an API call. Sort of like if lambdas would run CI jobs for the code to execute first if they hadn't run since the code was last updated.
- js8 6y agoI don't think that's quite true, I think the closest thing to that on mainframe is that databases can dynamically (JIT) compile the programs in query languages (SQL, DL/I) that used to be compiled statically (AOT).
- monocasa 6y agoI've definitely heard of shops that compile COBOL and PL/1 in response to CICS transactions if the stored source is out of date.
- js8 6y agoI think it's just poorly worded (or they indeed confused it with AS/400), and what they really mean is while technically yes, IBM mainframes run machine code that has been kept compatible for decades, today lots of old instructions are microcoded and the overall CPU architecture is so different that it amounts to recompilation in hardware. So the particular choice of assembler language doesn't really matter anymore.
- p_l 6y agoI'd suspect it's a bad interpretation of how microcoded computers work, as on first contact they do sound like virtual machines like that.