The SAT 1 math exam contains a little knowledge of algebra in high school, but you have probably learned all the math concepts covered in the SAT 1 math exam (and the exam instructions will contain most of the simple formulas you need).
The SAT writing test includes correcting wrong questions and a simple propositional composition. The test sites for correcting mistakes include simple grammatical concepts such as subject-predicate agreement and sentence juxtaposition structure.
SAT reading test includes supplementary sentences and reading articles to answer questions. One third of the reading test is to test your vocabulary directly (supplementary sentences) or indirectly (reading questions and answers). If your vocabulary is not big enough, you will face great challenges in this exam.
So besides vocabulary and basic mathematical concepts, you don't need to know much to take the SAT. Many students have heard that SAT is an intelligence test. Like an academic IQ test, it's not. SAT tests the speed and accuracy of reading and analyzing basic mathematics, reading and correcting problems.
Note, I'm not saying that you can analyze how deep the problem is.