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It would be interesting to know more about the sources for this article because while nothing seems outright wrong, some details seem a bit off. e.g. it was cal
by dboreham 3y ago
It would be interesting to know more about the sources for this article because while nothing seems outright wrong, some details seem a bit off. e.g. it was called "OS/2-NT", not "NT OS/2" (unless that was the internal name at some point); while some NT features are obviously copied from VMS (i/o completion ports from $QIO), the article's mention of IRQ level is off -- that comes from the CPU design and is present in most CPUs going back a couple decades prior.
- JdeBP 3y agoActually, it isn't. I've implemented an IRQ level like system on Intel Architecture, and the operating system concept really doesn't match the processor's and interrupt controller's architectures very well at all until local APICs enter into the picture. Without a local APIC, one has to do tricks like re-issue interrupts with INT instructions in order to implement the NT interrupt model. The IRQ level concept may have antecedents in earlier systems from the 1980s, but it does not originate with the Intel-based Personal Computer AT architecture of the time, with its dual 8259s, EOIs, IF, and whatnot.