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PROFESSOR: Having looked at the quizzes in a preliminary fashion, I come to the conclusion that some notes on tensors would be useful for the remainder of the term. So at great pain and personal sacrifice I will endeavor to [INAUDIBLE] All right, let me remind you of where we were a week ago-- before a slight unpleasantness intervened-- and we had just begun to look at the properties of a very useful surface, the representation quadric. And we said that to define it we would take the elements of a second rank tensor, something of the form A11, A12, A13, A21, A22, A23, A31, A32, A33. And we'd use those elements as coefficients in a second rank, a quadratic equation, of the form Aij Xi Xj equals 1. OK, so the Xi and Xj are the coordinates in our three-dimensional space. And the set of coordinates that satisfy this equation-- setting the right hand side equal to a constant-- will define some surface in space. And it's going to be a surface that is a quadratic form, s...

PROFESSOR: Now having cut DNA, we then need to do something else. What's the next thing we have to do? AUDIENCE: Paste it. PROFESSOR: Paste it right. Oh, I put past. It should be paste. There we go. We should paste it. So, how are we going to paste our DNA? So let's take some human DNA. We'll take your human DNA. We'll add EcoR1 to it. And your human DNA is going to get cut up in lots of little pieces of length about 4,000. And I'm writing R1 at the ends because these pieces of DNA have EcoR1 sites. Now, I can take that human DNA and I can combine it with other pieces of DNA. Here's a piece of DNA. Remember it had this overhang like that. T-T-A-A was this piece here of human DNA. And I could take another piece of DNA that matched it a A-A-T-T. And it doesn't have to be human. It could be something else. It could be zebra. Some human DNA, some zebra DNA, and by that base pairing of those four bases, they'll sort of stick. It's not that s...

Having talked about the storage resources provided by the Beta ISA, let's design the Beta instructions themselves. This might be a good time to print a copy of the handout called the "Summary of Beta Instruction Formats" so you'll have it for handy reference. The Beta has three types of instructions: compute instructions that perform arithmetic and logic operations on register values, load and store instructions that access values in main memory, and branch instructions that change the value of the program counter. We'll discuss each class of instructions in turn. In the Beta ISA, all the instruction encodings are the same size: each instruction is encoded in 32 bits and hence occupies exactly one 32-bit word in main memory. This instruction encoding leads to simpler control-unit logic for decoding instructions. And computing the next value of the program counter is very simple: for most instructions, the next instruction can be found in the followin...