ATA stands for "AT Attachment"; electrically it is the same as the ISA bus, so these old controllers are not really controllers, they are merely adapters. I'm pretty sure they all perform the same.

ShovelKnight wrote on 2020-06-29, 10:05:

ATA stands for "AT Attachment"; electrically it is the same as the ISA bus, so these old controllers are not really controllers, they are merely adapters. I'm pretty sure they all perform the same.

Interesting thanks, I thought some kind of advanced internal features may be there. I've seen in the bios an "I/O recovery delay" in BCLK values and lowering it seems to improve disk speed. Default was 12 BCLK and I went down to 4 and still seems ok. Does it affect all the ISA cards or only the I/O one? Which values is consider safe for stability and speed?
Thanks

Yes it affects all ISA cards. There is no general answer to which value, it depends on your specific system and cards. Drop it as low as you can while maintaing stability and test thoroughly

I'm updating this to ask which are the latest chips that were built for ISA I/O controller cards? I mean is it possible that none of these many different brands chips (some dual chips, some single chip) didn't have any internal features to "speed up" the general disk speed/access time? No features at all?

not really they are just bus transceivers and address decoders

caching disk controllers for ISA did exist, but that's a whole different beast

Check out this question 3.6 of this contemporary FAQ: http://www.faqs.org/faqs/pc-hardware-faq/part2/
In my own experience, multi-sector transfer aka block transfer is indeed the biggest impact on performance. The FAQ is suggesting that if your BIOS doesn't have a block transfer option (my 486 does have one) then to look for "dqwik110.zip" so that might be worth a try.

Thanks both for the answers. These are my Speedsys results with my 386DX40 with UMC865/863F based 1994 I/O card and a 520MB Seagate disk:

Disk: avg seek time: 14,64ms
max seek time: 23,36ms
track to track: 3,01ms
random access time: 25,75 ms
buffered read speed: 1191Kb/s
linear verify speed: 1747Kb/s
Final Score: 23,52

Are they already at the ISA limits in your opinions?

The FAQ seems like ISA is capable of more than that (it says about 2 megabytes per second) and that it's the drive. It's worth trying out whether your drive supports multiple-sector transfers. Anything about them in your BIOS? or you'll have to try the driver. What that does is allow the machine to transfer 4K or 8K per IRQ rather than just 512 bytes.

Most of my boards I benchmark max out at 1.7MB/sec of linear verify speed with my SD card, so I think this is a fairly standard speed. This is a good info actually when benchmarking VLB controllers for example because you can see the effects of the VLB card's drivers thanks to this. Basically, 1.7MB/sec = ISA speed and anything over means that the drivers are working.