If you have an internet connection, binary disk 1 may be all you need. It includes the installation system and the most commonly used packages. The installation system can download any other packages you need over the network. The other disks include all the other packages in very roughly decreasing order of popularity.
Please refer to section 5 of the Debian GNU/Linux installation manual for details on booting the installation system.
These disks' reference numbers are:
30r0-sparc-1 [ file list ]
30r0-sparc-2 [ file list ]
30r0-sparc-3 [ file list ]
30r0-sparc-4 [ file list ]
30r0-sparc-5 [ file list ]
30r0-sparc-6 [ file list ]
Also available is a crippled USA-friendly version of disk 1. You probably don't want this. It's just like the full non-US version, but with certain packages which may interact badly with some US laws removed. The other disks don't have crippled versions because they don't contain any of the affected packages.
The reference number is:
30r0-sparc-1-US [ file list ]
// Sat Jan 18 14:06:58 2003 GMT