CS61C-disc01

discs1
aims: a conceptual check

1.1 true (not exactly) 1.2 false 1.3 false 1.4 true

2 (a) 1. 0b10010011 0x93 0d147; 2. 63 0b0111111 0x3F the later the same method, so skip it

2 (b) 1. 0b1101001110101101 skip the same way

2 © 2^16 = 64 Ki the same skip

2 (d) 2 Ki = 2^11 skip the same

3 (a) two’s 127 -128 (don’t understand the homework when I was doing them)

3(b) biased not know exactly

3© 3

3(d) 256 unsigned No such integer? 1to256 instead of 0 to 255

3(e)(拍照纸上)

​ Thought: we assume that x abcdefgh with 8 bits. a,b,c,d,e,f,g,h all represent 0 or 1.

3(f)

​ why the three radices shine?

base 10: maybe that’s because people have 10 fingers
​ base 2: It’s better for computer. But why it’s better for computers, I don’t know.

​ base 16: one digit of base16 can symbol 4 digits of 2. But why base 8 is not used. I don’t know neither.

Extracts from the solution:

Binary signals are less likely to be garbled than higher radix signals, as there is more “distance” (voltage or current) between valid signals. Additionally, binary signals are quite convenient to design circuits, as we’ll see later in the course.

4(a) 2 overflow reference: Two’s Complement Overflow Rules

4(b) 1.8bits 2.7bits 3. ? an: 7bits 64 numbers 4. 2^43 < 12* 2^40 < 2^44