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Ch375 alternative, so can also read External CD/DVD USB Drive support.. or even USB Floppy?

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First post, by jdredd

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I am dumb so please forgive.

But what kind of effort, if possible, would it ever be to get the CH375 alternative chipset for a new ISA card to interface with an external USB CD/DVD drive or even USB Floppy drives, along with thumb drives?

I only ask because I have the IBM Model 30 system and an old CD with lots of old Pascal 80s/90s source code I wanted to copy over quickly.

Which just required me to copy it to a thumb drive, and jam into CH375 card that is in the IBM.

Which worked, but got me thinking, what would it take to allow external drives beyond thumb drive?

Reply 1 of 1, by Ryccardo

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At the USB MSC (≈ SCSI) level, a data CD/DVD isn't very different from a flash drive when it comes to reading plain data - though it would come with the usual problems with a directly connected optical drive (2048 byte sectors and "uncommon" filesystems); as you may know, MSCDEX and clones actually simulate a network share as to bypass the whole block device implementation, so depending on the limitations of that chip it could be "easy" (all software) to impossible!

Floppies, again even before considering this weird interface, are comparatively worse - CHS-only disk (that can have a variety of geometries) meets all-LBA interface where in theory you can freely-ish configure the mapping but the products you can actually buy prove otherwise, you might get away with reading and writing the plainest DOS-formatted 1440k disk but low level formatting won't happen without special drivers that may be impossible…

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