On Sat, 27 Jun 2020, W2HX via cctech wrote: > Could it be related to the fact that it is a 2GB SD card and I believe > IDE controllers of that day could only address something like 500MB?
Except for a few sophisticated caching host bus adapters and ATA RAID controllers that presented their own software interface an ATA host bus adapter was essentially a pass-through device with an address decoder and a bunch of tri-state logic buffers. The IDE controller was (as the name suggested) integrated with the ATA device itself. Therefore all the simple ISA host bus adapters for ATA devices supported even the LBA48 mode as they did not interpret values passed through the control registers, which resided on the ATA device (similarly ATAPI support can work, which issues commands in the data stream rather than via the ATA command register). The limitation came from solely from the PC BIOS interface; once an OS has been booted that could drive ATA devices itself you could use the full capacity of any ATA device. Maciej
