The SOLiD platform follows these general steps outlined below:
1) Library preperation
This step can be done in one of two ways. The first way is by fragment analysis and the second is mate paired. The difference is basically whether you have one fragment of unknown DNA or two fragments of unknown DNA sepaerated by an adampter (known) piece.
2) Adapter ligation
This step involves attaching adaptors (known sequence tags) to your unknown fragments so you can pick them out at a later time for assembly.
3) Hybridization to bead
In this emultion PCR step you are attaching (and amplifying) the fragments to a clonal beads
4) Covalently attach bead to glass slide
5) Ligation of probe (and sequencing)
In this step you add a primer that finds your adapter sequence previously attached and it then undergoes attation of florescent nucleotides that emit colored light as each is incorporated (similar to the other next gen chemistry). This is considered a cyclic ligation step.
The manufacturer claims a 99.99% efficiency.
For a good overview look here
Source information was from the ABi manufacturer website.
See also the Wikipedia article, "2 base encoding"