draft -- only the + version loads so far

cd /tftpboot/
mkdir memtest/
cd memtest/

wget https://www.memtest86.com/downloads/memtest86-iso.tar.gz
tar xvzf memtest86-iso.tar.gz

wget http://www.memtest.org/download/5.01/memtest86+-5.01.bin.gz
zcat memtest86+-5.01.bin.gz > memtest86+-5.01.bin

vi /tftpboot/pxelinux.cfg/default

label MemTest86
linux memdisk
initrd Memtest86-7.4.iso
append iso
#append iso raw

label Memtest86+
kernel memtest/memtest86+-5.01.bin

refs.