Hi,
I dont think there are any specific detailed hardware specs for the BMR Boot Server other than the OS (and the corresponding hardware) architectures on which BMR is supported.
So the BMR Boot Server is currently supported on Solaris-SPARC, HP-UX PA-RISC, AIX, RHEL/SuSE x86 & x64, Windows x86 & x64 (in 6.5.4).
BMR Boot Server binaries are all 32 bit on Solaris,, PA-RISC, AIX, Linux & WIndows x86.
For most purposes your boot server should have:
1. Network access in case you plan to boot your BMR clients over network.
2. CD/DVD Writer in case you plan to make SRT ISOs and burn them on CD/DVD and boot your clients using the same.
3. In case of Solaris/AIX, about 10-12 GB of free space if you plan to make ISOs out of SRTs.
4. Decent processor/RAM since for network boot scenarios, your boot server will need to run a bunch of daemons (not very heavy duty though) like tftpd, rarpd, dhcpd etc.
Does this help you?
~Amol.