End of an Era for the ISA Bus

What is a PC? Certainly the specification for PCs has changed almost entirely since the earliest examples. Another element of the original PC architecture was finally consigned to the dust this month with the announcement tucked away on the WHDC site that support for the ISA bus would be discontinued in future releases of Windows beyond Windows Vista. So I guess it's time to consider upgrading my old IBM PS/2!

Comments (11)

  1. Anonymous says:

    Didn’t the PS/2 use MCA bus?

  2. Tim Sneath says:

    Actually, the most basic models of the PS/2 had an ISA bus, if I remember rightly – only the later models switched to MCA. But I’m bluffing anyway, of course – hopefully the PS/2 I once used has long ago been consigned to the big blue elephant graveyard.

  3. exportgoldman says:

    Are you people out of your minds, why on earth has support for ISA not been dropped already? I have not seen a new computer with ISA for about 6-8 years now.

    How much of this new Vista code is legacy code like this? How do you even TEST it?

  4. Anonymous says:

    "Actually, the most basic models of the PS/2 had an ISA bus, if I remember rightly – only the later models switched to MCA."

    That’s mostly correct. IBM shipped four models as part of the initial PS/2 ‘wave’: the 30, 50, 60,and 80. Only the 30 used ISA (8-bit). It also was unique in that it used an 8086, making it unable to run OS/2.

    Later on, IBM introduced a model 25 (all-in-one, low-end) and a model 30/286 that both also used ISA.

    At the high end, MCA was also used in servers, RS/6000 workstations, and possibly ES/9000 mainframes.

    "hopefully the PS/2 I once used has long ago been consigned to the big blue elephant graveyard."

    I worked on OS/2 Lan Server back in 1995 as a summer intern. My desktop was one of the original PS/2 model 80’s from 1987, but upgraded to 20MB of RAM. Believe it or not, with all the memory, it wasn’t as dog-slow running OS/2 as you would probably have thought.

  5. Anonymous says:

    "How much of this new Vista code is legacy code like this? How do you even TEST it? "

    Have you seen SLOC figures for Windows? Windows NT was something like 4M LOC, Windows XP close to 50. Just based on that, my hunch is that legacy hardware support is a relatively small (but sometimes annoying) backwater in the source tree.

  6. Anonymous says:

    there’s a small but non-zero population of machines in the "semi-embedded" realm running XP (XP embedded, the modular version) and chugging along with ISA busses interfaced to…well, everything.

    though I’m not sad to see it go, the ISA bus was at least a robust, easy-to-work-with design on the hardware side. it achieved that by neglecting software support (be sure to set your DIP switches to match the IRQ and address expected by your drivers!), but it’s great for the embedded world.

  7. Anonymous says:

    Yes, we had an IBM PS/2 Model 30 in our office when they came out, and it was ISA, not MCA. I seem to remember they were also pretty expensive – and quite crap, actually. It did of course have the big red power switch of death (with a fantastically Heath-Robinson mechanism inside, which involved a foot long piece of metal that *mechanically* linked the switch at the front of the case to the rocker switch on top of the PSU inside the case. Awesome.)

    Of course, it was the machine that first introduced the idea of using the same mini-din connector for mouse and keyboard, hence the PS/2 name.

    What a great idea that was. I remember all of us in the IT support office were agog that IBM decided to use the same plug for the devices, so you could easily plug them in the wrong way around, which could confuse you for a long time. Luckily, IBM put the two sockets right next to each other with tiny legends indicating which was which. (A feat only surpassed by Creative Labs engraving the legends on the back of their sound cards, so you normally need a scanning electron microscope to work out which is which.)

    Still, it only took about 10 years before PC manufacturers started colour coding the mouse/keyboard plugs, eh?

    Sometimes I think these people shouldn’t be allowed the keys to anything important.

  8. Edge says:

    @ exportgoldman:

    One of my dual processor systems was built in late 2000/early 2001, and it had an ISA slot on the motherboard (which actually went to use with an older modem!).. but I imagine by the time Windows Vista + 1 ships the spec’s required probably won’t even cover anything that could have had an ISA slot to begin with.

    On the other hand, the beta of Vista seems to run as well as Windows XP on the old Pentium III/ISA system.

  9. Anonymous says:

    You can still buy a brand new motherboard designed for a P4 with an ISA slot in it. Quite important in a number of areas like industrial control PC’s. They are not hard to find though they are a specialist item now.

    In my area which is lab equipment shelling out say $80,000 for a new bit of lab equipment because the PC has broken down and the interface card is ISA is not funny. That is at the cheaper end of the scale as well. For some items it could easy be a seven figure sum.

    I guess Microsoft don’t really understand this.

  10. Anonymous says:

    Correct me if I’m wrong, but doesn’t the Serial/Parallel and PS/2 Ports still use the ISA Bus to connect internally to the PCI to ISA Bridge?

    So technically, your Keyboard and Mouse (Unless USB) still need the ISA Bus?

  11. Anonymous says:

    I am currently looking to replace an old library system with a ISA card required to run database software. Like the above posters have stated, in Enterprise, it is NO joke. Dell, Gateway, Hp and Lenovo (IBM) no longer ship anything with ISA, so we are going to have to piece something together. But we will NOT shell out tens or G’s for the newest system ver. when our current one functions just fine, save a failing MB.

    ISA will be around for a LONG time to come.


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