On the strange joys of mainframe OSes that have survived into modern times

Re:On the strange joys of mainframe OSes that have survived ... by __d on Sunday September 25, 2022 @05:09PM (#32976264)

I think those definitions are somewhat complicated, because micro-computer architectures have gradually adopted features (perhaps in reduced form) from their mini-computer and mainframe counterparts.

So, mainframes have channel controllers, and micro-computers don't. But a modern micro-computer Ethernet driver might run some software on the NIC. It's not really a channel and yet the architectural distinction is blurred.

The distinctions made more sense in the 80's, when the lines were clearer.

But I think the point is valid: the micro-computer architecture has taken over the industry, and some things of value have been lost.

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Re:On the strange joys of mainframe OSes that have survived ... by __d on Sunday September 25, 2022 @05:24PM (#32976425)

Similarly, the "bus" of a micro-computer started out as a pretty simple thing: parallel, 8 bits of data, 16 bits of address, with memory-mapped or I/O-mapped fixed-function peripherals managed by the (single) CPU. Memory and I/O devices on the same bus.

But the modern PCIe "bus" is really more of a packet-switched network. Memory is now separate (although, see CXL). Devices on that network can talk directly to each other, or to the CPU. In some ways, this is closer to a mainframe architecture.

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Re:On the strange joys of mainframe OSes that have survived ... by rahen on Sunday September 25, 2022 @05:44PM (#32976629)

It absolutely is. IBM started to bring mainframe features to the PC architecture with its PS2 line. The PS2 microchannel architecture (MCA), in particular, was inspired by the 360 and became itself the inspiration for the PCI bus.

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