When I said: "boot: tc vga=771 ide_generic.probe_mask=0x3f" at the TC 3.8.4 boot prompt, then the desktop showed up, but the mouse pointer was frozen. With "boot: tci vga=771", the startup hang at "Loading extensions...". "boot: mc vga=771 ide_generic.probe_mask=0x3f" took me to the command prompt, and now "fdisk -l" and "cat /etc/fstab" showed me all partitions on hda (harddisk) and sda (pendrive), but "startx" wasn't found, and "/etc/sysconfig/tcedir" didn't exist. Now, "boot: tc vga=771 ide-pci-generic.all-generic-ide" solved the mouse problem: It was movable, the harddisk was readable, but "/etc/sysconfig/tcedir" still didn't exist.
Then I tried the same at the TC 6.4.1 prompt, booting the ISO file from harddisk. The prompt looks different here, there is no "boot:". After "/boot/vmlinuz initrd=/boot/core.gz loglevel=3 cde showapps desktop=flwm_topside", I added: "vga=771 ide-pci-generic.all-generic-ide", and then I stuck again at the "tc@box:~$" command prompt, with "fdisk -l" only mentioning sda1. So I set all my hope on the "ata_generic.all_generic_ide=1" kernel parameter. To my surprise, "fdisk -l" now listed the harddisk partitions as sda1, sda2, sda5, sda6, and the pendrive as sdb1. I could mount and read sda1, where the "CorePlus-6.4.1.iso" file lies. However again, there was no desktop, no "startx", just a link pointing from "/etc/sysconfig/tcedir" to "/tmp/tce", which contained an empty "optional" subdirectory. "fromISOfile" said: "Need root privileges", "sudo fromISOfile" said nothing.
In my attempt to chain boot TC 6.4.1 via FreeDos from USB, I could pass the required kernel parameters to loadlin on the DOS command line. When I redirected loadlin's output to a log file, I read an error message that I didn't notice yesterday: "can't open image file for initrd". However, when I simply moved the "boot" and "cde" folders up one level to the top directory and changed the command line accordingly to "loadlin d:\boot\vmlinuz root=/dev/sdb1 initrd=d:\boot\core.gz ro cde vga=771 ata_generic.all_generic_ide=1", only a loadlin warning remained: "loading above 16MB using INT15". The "waitusb=5" parameter seemed not to be required. "tce-status -i" now listed "Xlibs Xprogs Xvesa aterm firmware fluxbox flwm icewm iw jwm kmaps openbox wbar wifi". Now "startx" was present, but "failed in waitforX".
Since this was new, I booted again the "CorePlus-6.4.1.iso" file from harddisk with "vga=771 ata_generic.all_generic_ide=1" kernel parameters. "tce-status -i" then listed the same 14 items, but "startx" failed because the "Requested flwm_topside could not be loaded". So I booted again and selected "FLWM Classic Window Manager". This again "failed in waitforX". And it was quite the same when I added those kernel parameters in "menu.lst" to boot the frugal installation on the sixth harddisk partition with EXT3 filesystem. In short, I can access all drives by now, but I still can't get up the desktop in current Tiny Core Linux!