Appendix 5 — Numbers, Notation and ASCII

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Number Prefixes Used In This Course

Form	Meaning	Example
42	decimal	42
$2A	hexadecimal	$2A
%00101010	binary	%00101010
0b00101010	binary (alternate form accepted by AZM)	0b00101010

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Hex Digit Table

Hex	Binary	Decimal
0	0000	0
1	0001	1
2	0010	2
3	0011	3
4	0100	4
5	0101	5
6	0110	6
7	0111	7
8	1000	8
9	1001	9
A	1010	10
B	1011	11
C	1100	12
D	1101	13
E	1110	14
F	1111	15

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Common Hex Landmarks

Value	Decimal	Why it matters
$00	0	zero byte
$0F	15	low nibble all set
$10	16	one hex digit boundary
$1F	31	5-bit max unsigned
$20	32	ASCII space
$7F	127	7-bit signed max / ASCII top
$80	128	sign bit set
$FF	255	byte all set / -1 in two's complement
$0100	256	common code base in this course
$7FFF	32767	signed 16-bit positive max
$8000	32768	high bit set in a word / common RAM base in examples
$FFFF	65535	word all set / -1 as 16-bit two's complement

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7-bit ASCII (0–127)

Dec	Hex	Character	Meaning
0	$00	NUL	control code
1	$01	SOH	control code
2	$02	STX	control code
3	$03	ETX	control code
4	$04	EOT	control code
5	$05	ENQ	control code
6	$06	ACK	control code
7	$07	BEL	control code
8	$08	BS	control code
9	$09	TAB	control code
10	$0A	LF	control code
11	$0B	VT	control code
12	$0C	FF	control code
13	$0D	CR	control code
14	$0E	SO	control code
15	$0F	SI	control code
16	$10	DLE	control code
17	$11	DC1	control code
18	$12	DC2	control code
19	$13	DC3	control code
20	$14	DC4	control code
21	$15	NAK	control code
22	$16	SYN	control code
23	$17	ETB	control code
24	$18	CAN	control code
25	$19	EM	control code
26	$1A	SUB	control code
27	$1B	ESC	control code
28	$1C	FS	control code
29	$1D	GS	control code
30	$1E	RS	control code
31	$1F	US	control code
32	$20	space	printable
33	$21	!	printable
34	$22	"	printable
35	$23	#	printable
36	$24	$	printable
37	$25	%	printable
38	$26	&	printable
39	$27	'	printable
40	$28	(	printable
41	$29	)	printable
42	$2A	*	printable
43	$2B	+	printable
44	$2C	,	printable
45	$2D	-	printable
46	$2E	.	printable
47	$2F	/	printable
48	$30	0	printable
49	$31	1	printable
50	$32	2	printable
51	$33	3	printable
52	$34	4	printable
53	$35	5	printable
54	$36	6	printable
55	$37	7	printable
56	$38	8	printable
57	$39	9	printable
58	$3A	:	printable
59	$3B	;	printable
60	$3C	<	printable
61	$3D	=	printable
62	$3E	>	printable
63	$3F	?	printable
64	$40	@	printable
65	$41	A	printable
66	$42	B	printable
67	$43	C	printable
68	$44	D	printable
69	$45	E	printable
70	$46	F	printable
71	$47	G	printable
72	$48	H	printable
73	$49	I	printable
74	$4A	J	printable
75	$4B	K	printable
76	$4C	L	printable
77	$4D	M	printable
78	$4E	N	printable
79	$4F	O	printable
80	$50	P	printable
81	$51	Q	printable
82	$52	R	printable
83	$53	S	printable
84	$54	T	printable
85	$55	U	printable
86	$56	V	printable
87	$57	W	printable
88	$58	X	printable
89	$59	Y	printable
90	$5A	Z	printable
91	$5B	[	printable
92	$5C	\\	printable
93	$5D	]	printable
94	$5E	^	printable
95	$5F	_	printable
96	$60	`	printable
97	$61	a	printable
98	$62	b	printable
99	$63	c	printable
100	$64	d	printable
101	$65	e	printable
102	$66	f	printable
103	$67	g	printable
104	$68	h	printable
105	$69	i	printable
106	$6A	j	printable
107	$6B	k	printable
108	$6C	l	printable
109	$6D	m	printable
110	$6E	n	printable
111	$6F	o	printable
112	$70	p	printable
113	$71	q	printable
114	$72	r	printable
115	$73	s	printable
116	$74	t	printable
117	$75	u	printable
118	$76	v	printable
119	$77	w	printable
120	$78	x	printable
121	$79	y	printable
122	$7A	z	printable
123	$7B	{	printable
124	$7C	|	printable
125	$7D	}	printable
126	$7E	~	printable
127	$7F	DEL	control code