If Knoppix is booted from an external USB CD-ROM drive, it boots the kernel, but then it cannot read the filesystem from the CD, and leaves the user to a minimal shell.
It is possible to boot in "expert" mode, provided one has the modules usbcore.o, usb-uhci.o and usb-storage.o in a floppy disk. In "expert" mode, when asked if one wants to load more modules from a floppy, the three above modules should be loaded. In this case, a "SCSI" device is recognized (usb-storage makes USB devices look like SCSI ones) and Knoppix is booted from there.
So, please, include those modules in miniroot.gz. This would make booting possible for non-experts too.
A-Tech 8GB DDR3 1600 PC3-12800 Laptop SODIMM 204-Pin Memory RAM PC3L DDR3L 1x 8G
$13.99
Samsung 16GB 2Rx4 PC4-2133P DDR4-17000 1.2V RDIMM ECC Registered Server Memory
$16.29
HyperX FURY DDR3 8GB 16GB 32GB 1600 MHz PC3-12800 Desktop RAM Memory DIMM 240pin
$12.90
Samsung 8 GB PC4-17000 DDR4-2133 1Rx8 DDR4 Desktop Memory HP P/N 798034-001
$10.00
A-Tech 16GB 2 x 8GB PC3-12800 Laptop SODIMM DDR3 1600 Memory RAM PC3L 16G DDR3L
$27.98
A-Tech 8GB PC3-12800 Desktop DDR3 1600 MHz Non ECC 240-Pin DIMM Memory RAM 1x 8G
$13.99
Kingston HyperX FURY DDR3 8GB 16GB 32G 1600 1866 1333 Desktop Memory RAM DIMM
$13.25
32GB (4X8GB) DDR3 PC3-12800 1600 NON ECC LOW DENSITY MEMORY F3-12800CL10Q-32GBXL
$32.00
A-Tech 256GB 4x 64GB 4Rx4 PC4-19200 ECC Load Reduced LRDIMM Server Memory RAM
$287.96
A-Tech 64GB 4x 16GB 2Rx4 PC4-17000R DDR4 2133MHz ECC REG RDIMM Server Memory RAM
$87.96