Well it’s all going to be limited to ISA bus speeds so anything using flash memory will hit that ISA speed restriction.

But the SSD should have the fastest seek time regardless of adaptor.

What would be the fastest controller card like specific model I guess I could start there,

"Some sort of IDeE card and a ide to sata with ssd?"

Well it’s all going to be limited to ISA bus speeds so anything using flash memory will hit that ISA speed restriction.[..]

Hi, good morning! That reminds me of something else.
The ISA-based IDE controllers are merely host adapters.
That means the IDE port was running at ISA bus speed.
So if you have an overclocked ISA bus (say 10 to 16MHz), the CF card will also communicate at a higher speed than normal! 🙂
Anyway, it just somes to mind.

Maybe that's useful to keep in mind if we continue to experiment with all sorts of IDE controllers.

The PCI controllers arw decoupled from ISA speed, of course.
But if we overclock the PCI bus or VLB bus (Intel 486DX50 system), similar things may happen.
Depending on the type of IDE controller. If it's too intelligent/advanced,
it may maintain normal IDE I/O timings no matter what.

PS: Caching IDE controllers may be useful, still.
They won't increase performance for CF cards, though. Troughput, I mean.
Access time might be a little bit faster, though.
These cards had 80186 "CPUs" often (which rather were early SoCs or MCUs) that run complex caching algorithms.

Sphere478 wrote on 2022-07-20, 04:59:

What would be the fastest controller card like specific model I guess I could start there,

Specific model is difficult, but SCSI is likely to have the advantage over IDE.

If you have a nice SCSI card then using that over a generic IDE card would be the best option.

What motherboard you plan to use ?

pshipkov wrote on 2022-07-20, 07:20:

What motherboard you plan to use ?

^^More detail about the build would useful. Of course this has been discussed a number of times for at least the last three decades. Any results from a internet search at all?

A few years ago I bought an Adaptec AHA-1542CF SCSI ISA card and SD2SCSI adapter... wanted to test it on 286 and 386 but didn't find the time to test it so far 🙁

Looking into my test notes, Adaptec AHA-1542CF with SD2SCSI (v6) device can transfer about 1636 kB/s on 8 MHz ISA and 1909 kB/s on overclocked 14 MHz ISA.

For comparison VLB/PCI Adaptec 2842/2940 can do about 8000 kB/S (likely narrow SCSI-2 limit).

ISA will be the bottleneck here, not the choice of IDE/SCSI/flash/whatever.

A PCI/VLB IDE solution will be MUCH faster than an ISA SCSI solution.

On a PC that slow you will likely not notice any difference between IDE/SCSI/flash even on PCI.

Given your predeliction for Socket interposers and the like: Socket 3 provides a 486 bus. If the motherboard only offers ISA slots, it would still theoretically be possible to get a local bus and either use it directly (highest performance, but good luck getting an actual slot to work) or add a PCI bridge, which would limit performance, but be much easier to exploit. Imagine a So1/2/3 interposer with 486 PCI bridge chip and a ribbon cable to a PCI slot (or two or three) somewhere.

But such flights of fantasy aside, with the ISA bus bandwidth is very dependent on CPU usage. The less the CPU has to do with the bus, the better the net performance. That's why SCSI potentially outperforms IDE: even though raw performance might be lower, if the bus can run smoother it might win. I wonder in that case whether on an ISA bus, the much maligned caching IDE controller might not get peak performance (particularly when paired with CF).

IDE CF card is fast enough for old CPU.

Fastest ISA storage controller? The one with DMA support.

Jo22 wrote:

But if we overclock the PCI bus or VLB bus (Intel 486DX50 system), similar things may happen.

Yes and no. You can improve it if your speed is less than protocol limit. And lets not forget that CPU is also a big limitation in PIO mode.

Great replies, thanks all!

pshipkov wrote on 2022-07-20, 07:20:

What motherboard you plan to use ?

It’s the gateway 2000 😀

Gateway 2000 overdrive build

mpe wrote on 2022-07-20, 09:07:

Looking into my test notes, Adaptec AHA-1542CF with SD2SCSI (v6) device can transfer about 1636 kB/s on 8 MHz ISA and 1909 kB/s on overclocked 14 MHz ISA.

For comparison VLB/PCI Adaptec 2842/2940 can do about 8000 kB/S (likely narrow SCSI-2 limit).

That’s a pricy unit 🤔

It makes sense as you guys say, a dedicated processor with dma.

So scsi to sd? Or just a really modern drive is sounding like a good route.

-

Tapping into the bus huh? Love it, so that would be like vlbus? Haha. Not even gonna jump off that deep end though haha.

I may order a tweaker for this though. Even though I don’t think any mods are needed on this setup. Might be able to test some out on the other processors I have.

Ugh.

Go SCSI - it will be faster on that system.
But in reality even IDE + CF will be juuuust fine.

SCSI isn't SCSI. There's SCSI, WIDE SCSI, SCSI 2 etc etc.. Three different connectors per generation, at least.

There are also dog slow SCSI controllers.
- Like that Trantor chip of the PAS16? How much did it offer? 500 KB/s?

It is implied that for ISA bus we are talking Adaptec AHA-1542CF.

Jo22 wrote on 2022-07-20, 18:41:

SCSI isn't SCSI. There's SCSI, WIDE SCSI, SCSI 2 etc etc.. Three different connectors per generation, at least.

There are also dog slow SCSI controllers.
- Like that Trantor chip of the PAS16? How much did it offer? 500 KB/s?

I had a standalone card with the same chip, AFAICR. Trantor T128, maybe ? Chip was an NCR 5380 or clone thereof . It was slow indeed.

16bit ISA is around 5MB/s.

Maybe this could hit this limit after modding for 16bit operation https://github.com/eigenco/frankenpi 😀
"This is an experimental project to connect Raspberry Pi with the help of cheap Cyclone IV board to 8-bit ISA bus to act as multiple different devices.
Currently RP can act as hard disk using an image"

rasz_pl wrote on 2022-07-21, 05:51:

16bit ISA is around 5MB/s.

At 8,33 MHz ("ISA").
That number is from vcfed, I suppose. 😉

@10 or 12 MHz, "ISA" or AT bus is not that bad, actually.
Provided that 0 wait states are used, I mean.

Im often impressed how quick a 286 can be if it's not being limited by an 8.33MHz bus.

16,66 MHz as a timing would be cool, because the clock rate would be exactly twice.

Unfortunately, that's too much for hardware made with a 8.33MHz speed limit in mind. 😔