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ISA Compact Flash Adapter

I don't think there's a size limit for what the ISA-CF can handle. That would be down to the XT-IDE Universal BIOS, and I don't think it has a problem with large drives. You're more limited by which version of DOS you're using and what size partition it can see. DOS 2.11 is pretty limited, only 16MB natively, but 32MB with a third-part format tool. DOS 3.3 supports 32MB partitions, and DOS 5 through DOS 7 (Win95) supports 2GB partitions. FreeDOS can supposedly recognize up to 2TB, which is an utterly ridiculous size for an XT/AT class machine.
That, and making sure the CF card supports PIO-8, which, of course, most of them do, but none of them will say on the packaging. Maybe do a google search to look for CF cards are known NOT to work with the Lo-tech card. I've only tested a few cards myself with my HX, but the old Canon and Sandisk cards seem to work, as well as those white and blue Chinesium ones from Amazon.
 
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The practical drive size limit for a Tandy 1000 is probably 8.4GB; the way DOS versions prior to Window 9x internally represent drive addresses (CHS) for BIOS calls is limited to that. FreeDOS may support LBA natively, I'm not sure off the top of my head?, but I don't think it'd be a great choice for most applications on an XT class machine.

blackepyon said:
That, and making sure the CF card supports PIO-8, which, of course, most of them do, but none of them will say on the packaging. Maybe do a google search to look for CF cards are known NOT to work with the Lo-tech card. I've only tested a few cards myself with my HX, but the old Canon and Sandisk cards seem to work, as well as those white and blue Chinesium ones from Amazon.
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Cisco switches and routers used CF cards to hold their firmware for many years, and used cards from them with Cisco house labels are really common on eBay, etc. I've had good luck with them. But it's rare to find them much larger than 512MB. (I have a couple 2GB ones, they're definitely outliers.)
 
Eudimorphodon said:
The practical drive size limit for a Tandy 1000 is probably 8.4GB; the way DOS versions prior to Window 9x internally represent drive addresses (CHS) for BIOS calls is limited to that. FreeDOS may support LBA natively, I'm not sure off the top of my head?, but I don't think it'd be a great choice for most applications on an XT class machine.
Click to expand...

Yeah, I've been trying to test hard drives on the XT-IDE card I built (based on Glitch's XT-IDE rev.4), as I put it through it's paces (I found a couple minor things I need to change for the next version, but the XT-IDE itself seems to function normally).

IMG_20191121_065828870.jpg

I do have a Maxtor 8.4GB drive, model 90840D6. XUB can detect and identify the model numbers of the larger drives, DOS and Checkit can "access" them, but can't seem to properly identify the geometry. I had a bunch at one point that had jumpers to limit the physical size to 2GB or something (from when that was still an issue), but I think I tossed those. I'm digging through my collection to see if I don't have a smaller IDE drive still floating around.

Note: I do have several smaller CF cards to play with, but I'm specifically trying to test compatibility with hard drives, since the XT-IDE rev.4 is supposed to be "true" IDE, and not just the 8-bit PIO that the Lo-Tech ISA-CF uses.
 
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