Modern motherboards don’t come with ISA slots, and almost everybody is fine with that. If you really want one, though, there are ways to get one. [TheRasteri] explains how in a forum post on the topic.
Believe it or not, some post-2010 PC hardware can still do ISA, it’s just that the slots aren’t broken out or populated on consumer hardware. However, if you know where to look, you can hack in an ISA hookup to get your old hardware going. [TheRasteri] achieves this on motherboards that have the LPC bus accessible, with the use of a custom PCB featuring the Fintek F85226 LPC-to-ISA bridge. This allows installing old ISA cards into a much more modern PC, with [TheRasteri] noting that DMA is fully functional with this setup—important for some applications. Testing thus far has involved a Socket 755 motherboard and a Socket 1155 motherboard, and [TheRasteri] believes this technique could work on newer hardware too as long as legacy BIOS or CSM is available.
It’s edge case stuff, as few of us are trying to run Hercules graphics cards on Windows 11 machines or anything like that. But if you’re a legacy hardware nut, and you want to see what can be done, you might like to check out [TheRasteri’s] work over on Github. Video after the break.
Really quite a nice hack but already covered? https://hackaday.com/2023/03/23/isa-over-tpm-to-your-pc/
Yes I knew I’d seen it before as I follow him on YouTube,
What’s more interesting are the 52 pages of comments on other folks attempts getting it working. Its been rumbling on a bit.
I knew i had seen the video before and probably from a HaD article.
I do note, the original article links to a no longer existing video. I remember one of his videos being about what he attempted to do but failed partially. and this later video probably was a more logical final video
In Estonian “isa” means father so…
millions of tech feet suddenly press down on your shoulders as they stand upon giants, quoting you for years to come
YMMV
I has some PCI-X to PCI bridges running with the PI7C9X111SL for supporting some legacy cards.
Variable outcomes.
Often it would be fine under linux but not windows – same machine.
Other times it would be the opposite. Which was interesting but not helpful :)
Mostly, two cards of the same type in the twin slot bridges would see one or the other never both.
Lot of stuff out there about tweaking BIOS settings which assumes it isn’t locked down (haha these days).
Ultimately if it’s mission critical you’ll find a way even it’s it’s not the way you wanted (stockpiling boards with PCI slots)
Could be interesting for folks with ADC sampling cards (think lab hardware, not audio stuff – audio is simple and slow). Data acquisition in the 100s of megasamples per second is bloody expensive (if you want the quality and several channels simultanously, not multiplexed, and longish time series).
ISA runs at 8 MHz maximum. It’s not going to work for high speed data acquisition unless the card has buffer memory.
“Socket 775” and “Socket 1155” are certainly odd ways to describe LGA775 Core 2 Duos and LGA1155 Ivybridge chips.
You’re right, of course, but you inspired me too look up and discover that Intel still does give use “socket” designations: LGA775 was “Socket T” and LGA1155 was “Socket H2”.
I’ve never heard anyone use those, and suspect that would’ve been even more confusing!
Including both the socket type/pin count and the processor name/generation is probably safest where Intel is concerned given that they’ve released pin-incompatible* CPUs for the same physical socket at least as recently as the Kaby Lake/Coffee Lake era.
*(though not as pin-incompatible as Intel claimed, as some Coffee lake CPUs can be shoehorned into older LGA1157 motherboards just by masking off some pins and patching the bios. Impractical, especially now, but a neat trick)
ugh, typos. “give use” in first paragraph should just be “use”, and “LGA1157” should actually be “LGA1151”.
Why? I worked in the industry for decades and we referred to them as exactly socket 775 or 1155 etc.. for instance 775 could be anything from single core p4 Prescott to core 2 quad yorkfields and 1155 could be sandybridge or ivybridge
i’d be inclined to do isa using rp2040 and a few i/o multiplexers (8 bit latches) :)
But then it wouldn´t appear as native to the system….
Yeah that’s the point :)
If i want ISA to appear as it did 30 years ago, i’ll use a 30 year old PC. If i’m trying to bring it into the future, i’m really trying to bring it into the future. Expecting honest “BIOS” sort of behavior out of a modern motherboard seems nuts to me, and an even further stretch to expect any OS to do the right thing with it. If you can make it work, more power to you, but we’re in an era. :)
If you have a specific ISA device you want to use on a modern PC, and are willing to write new drivers and possibly software for it, that approach makes total sense.
But the people excited about this sort of project (and there are a surprisingly large number) are absolutely not thinking that way. They’re getting a kick out of – or have a genuine use for – running old software (and OSes) on insanely fast modern-ish computers.
The holy grail for them that this approach offers is DMA, which can’t be implemented or emulated by any sort of bridge driver since the entire point of DMA is that it bypasses the CPU. and a lot of popular ISA cards (like the soundblaster series and various esoteric capture/storage cards) depend on it.
I just think it’s interesting to have bare-metal OSes like DOS running on modern hardware.
It’s not about performance, but all the cool new features of x86 processors that can be accessed easily
because DOS is single-tasking by default (yeah, there’s DESQView etc) and needs no task-switching and context-switching.
Imagine, things like SSE or AVX can be used via ASM directly.
That’s cool for writing super-fast console/computer emulators running on plain DOS.
The cool thing about DOS is that it can be used as a clean runtime for a specific application.
No Linux with its daemons involved, the computer directly boots into your application.
Plus, there are a dozen DOSes out there, not just MS-DOS and FreeDOS. It’s a whole platform, like *nix.
For example, by turn of century, DOS was used for arcade cabs.
Not 486es, but powerful Pentium II and III motherboards running at near a GHz.
A simple VGA to RGB cable and TSR were all it needs to re-program an ordinary VGA card to 15 KHz (the VGA CRTC is very flexible!).
The response time and everything was nice on plain DOS,
because the emulator basically ran directly on the hardware without any background tasks involved.
Anyway, it’s just one example.
The cool thing about having ISA bus is that it needs no microchips.
You can use bog standard, discrete TTL/CMOS ICs for your homebrew expansion cards.
ICs that don’t contain software, how cool is that!? 😎🩶
yeah i separate these…if i want to play xwing with an original soundblaster and awful pwm analog joystick, i have a 486 my friend found in a barn. i even found my authentic 1990s joystick on ebay in 2016. if i care that much about the soundcard, i care that much about the rest of the pc as well, i figure. i don’t understand wanting one part absurdly old and another part new, and not preferring to interface with it by proxy over usb.
https://github.com/FlyGoat/csmwrap