Maybe offtopic maybe an optimization task:

I noted that multi block transfer on my Isa system is max 16.
on my VLB system it’s max 128!

This might also be responsible for a large performance difference.

Not quite sure whether it’s a bios topic but what I could find so far that it simply lies in the nature of vlb allowing 128 sector transfers at once compared to max 16 sectors on Isa Bus

I also want to thank Douglar for the very interesting Cache Controller results. The linear read results are a bit disappointing to me 😒

Marco wrote on 2025-11-27, 06:32:

I also want to thank Douglar for the very interesting Cache Controller results. The linear read results are a bit disappointing to me 😒

I’m glad I did it. In hindsight, I guess it was pretty obvious that the max memory bandwidth could limit the i/o transfer for an IDE controller, but I didn’t expect to see it. The linear read speeds seem to be limited by the transfer rate between the storage device and the 286 on the controller. That’s tough to tweak unless you are up for hacking the controller ROM.

This isn’t a bus master isa ide dma controller, but it is a home brew 8 bit ISA controller that uses DMA https://www.lo-tech.co.uk/wiki/XT-CFv3

And there is bios support for it if you use this build of XUB: MODULE_8BIT_IDE_ADVANCED - Support for memory mapped and DMA based cards like JRIDE and XTCF

Edit: More info about JRIDE here: https://www.retrotronics.org/home-page/jride/

I dont expect the 286/20 to be the limiter. Why: My PIO transfer modes on a 386sx/25 were also above 3mb/s (via high isa).

More important: Fantastic remark with that MM I/O interface cards!

Question: Are you aware of any cards with 16Bit?

Update: As this is a new topic it might be consequent to open a dedicated thread for that question.

This card has some significant stuff going on--- Trying to figure out what chip it has.

https://theretroweb.com/expansioncards/s/prom … -pti-eidemax-ii

Hello, seems as if the card provides ext Int13 Support for drives attached to the Card and these attached to the MB Controller.
Couldn’t find more at the Moment.