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Comment by kristopolous | Hacker News Reader

There's ISA to USB devices for under $40 so you can hook the hardware up to a modern machine

Then I'm sure you can use one of the many emulator solutions on the market to bridge the rest and if none are suitable it can't be that hard, the data is making it to the machine...

I'll happily make it happen if you need to hack something like qemu, sounds like fun.

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I think a lot of these ISA cards are for industrial control in realtime systems, so the added latency of USB is not going to work.

Are you sure? We aren't in the world of USB 1.1 latency any more. Things have improved vastly since then.

There's still latency getting data DMAed through buffers from Host to slave no matter how fast the link is. It's also non-deterministic.

I found two people who measured latencies, one a PCIe parallel port and the other USB 3.0:

https://stackoverflow.com/questions/41987430/what-is-the-low...

https://stackoverflow.com/questions/13831008/what-is-the-min...

PCIe parallel port: 4-8us

USB 3.0: 30us

I believe a regular PCI or even ISA parallel port can be below 1us. Those are "real" buses, unlike USB and PCIe which are more similar to packet-switched networks.

I don’t know about ISA, but pci (not e) can easily be under 1us. It would be an odd design to have even that much latency.

As measured on the bus.

Theoretical one-way latency on PCIe 3.0 ×1 for a 256-byte packet is < 0.5µs. A single register write should be < 0.1µs.

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