Flashcards: From Bits to Meaning
1 What is a code?
An agreed mapping between signals or symbols and what they represent.
2 What is a signal?
An observable state used to communicate or store something.
3 What is a symbol?
A human-usable mark, word, character, or name that stands for something by convention.
4 What is a bit?
One binary digit: 0 or 1.
5 What does one bit distinguish?
Two possibilities.
6
What does 2^n count?
The possible patterns from
n binary choices.7 How many patterns can 6 bits represent?
64.
8 How many patterns can 8 bits represent?
256.
9 What is a byte?
8 bits.
10 Why does a byte need interpretation?
The same pattern can mean different things under different codes or contracts.
11 What is ASCII in the inspected source?
A 7-bit coded character set.
12
ASCII 01000001 represents what character?
A.
13
Text 12 is stored as what?
Character codes for
1 and 2.14 Compact binary 12 can fit in what byte pattern?
00001100.15 What does a shift code do?
Changes how later codes are interpreted.
16 What does an escape code do?
Changes interpretation for a following code or sequence.
17 What is a Boolean function?
A function from binary inputs to binary outputs.
18 What is a logic gate?
A physical device that implements a Boolean function.
19 What does a 1-bit register store?
One bit over time.
20 What does a 16-bit register store?
A 16-bit value over time.
21 What is RAM in Nisan/Schocken’s model?
Addressable registers that can be read or written directly by address.
22 What is machine language?
A formal code for instructions that control a hardware platform.
23 What is an assembler?
A program that translates symbolic assembly into binary machine code.
24 What is a Hack A-instruction?
A 16-bit instruction whose leftmost bit is 0 and whose remaining bits code a value.
25 What is a Hack C-instruction?
A 16-bit instruction with computation, destination, and jump fields.
26 What does CPU decode mean?
Interpreting instruction bits as control fields for hardware.
27 How can a black-and-white pixel be stored?
As one bit in a screen memory map.
28 What is a bitmap?
An image stored as a grid of pixel values.
29 What does an ADC do?
Converts an analog voltage level into a binary number.
30 What is the lesson’s central memory hook?
Computers store patterns; meaning comes from interpretation.
source anchors
Source Anchors
petzold-code-hidden-language-computer-hardware-software-2eChapter 1. Best Friends, near page 5 through page 7: codes.Chapter 2. Codes and Combinations, near page 10 through page 14: binary combinations.Chapter 3. Braille and Binary Codes, near page 16 through page 19: shift and escape codes.Chapter 9. Bit by Bit by Bit, near page 61 through page 64: bit.Chapter 15. Bytes and Hex, near page 170 through page 180: byte.Chapter 20. ASCII and a Cast of Characters, near page 271 through page 285: ASCII and text.Chapter 25. The Graphical Revolution, near page 344 through page 353: pixels, bitmaps, ADC/PCM sound.
nisan-schocken-elements-of-computing-systems-2e- Hardware introduction, near page 25: program text to machine language.
Chapter 1 Boolean Logic, near page 34 through page 39: binary values, Boolean functions, gates.Chapter 3 Memory, near page 85 through page 88: registers and RAM.Chapter 4 Machine Language, near page 97 through page 115: assembly, binary instructions, I/O maps.Chapter 5 Computer Architecture, near page 127 through page 129: data words, instruction words, CPU decode.Chapter 12 Operating System, near page 336, page 340 through page 347: strings, screen pixels, character bitmaps, keyboard codes.