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USB on an 8 bit ISA Bus, it is possible!!!


Veteran Member
Dec 28, 2011
Learn something new everyday... I was not aware that this existed- at all. Perhaps I should create a boot ROM for it someday...

Back to the topic. I'm not sure if there is a massive demand for using USB keyboard, USB sound codec or USB printer on vintage computers. But imo, using USB mass-storage does matter for the sake of convenience and cool. Actually, I have been using USB sticks on my 386DX-40 and DX4-100 for 2+ years. The product I use is a CH375 based ISA card with an USB port on its backplate (as pictured). Yes, it comes with a little (4kB) DOS driver that can be loaded by config.sys which adds a new DOS drive letter (H:\ for eg.) also visible under Windows 3.x. It allows me to use USB stick, USB card reader or USB external HD with my ISA rigs, including my 8088 XT clone (8-bit ISA), with reasonable r/w speed. It supports hot-swap and even boot from USB (if a boot ROM is installed). However, it may not be a general USB solution for ISA bus but just USB mass-storage only, and the storage has to be formatted in FAT (required by DOS). I have not yet tested it with USB hub or CD/DVD. But I do prefer its convenience over floppy disks, LL3 or FTP (command line).

So far, I'm just a user without putting any thought on what else this product can do with USB. I'm happy with its existing simplicity of use because that's all I need for my $18. Maybe it is not something truly belong to vintage computers. But it's another nice retrofit option similar to those modern LCD monitors, CF cards or FDB-based HDDs often seen in today's retro projects.

I bought it from a random online seller in China. I don't have a valid URL anymore (sorry) but full information about this product is easy to access by Googling with keywords: USB ISA CH375. That's why I didn't bother to post it here as I assume it's something known without mention.

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