How many characters does ASCII hold?

ASCII holds 128 codes, from 0 to 127. Of those, 95 are printable.

What is the ASCII code of a space?

A space has the code 32, which is 0x20 and 00100000.

Apply OR with 0x20 to get the small letter, and AND with 0xDF to get the capital letter.

ASCII maps the codes 0 to 127 to characters.

The codes 0 to 31 are control codes. The codes 32 to 126 are printable. The code 127 is delete.

Each code fits in 7 bits, so a byte holds one ASCII character with the top bit clear.

The code 65, which is the character A. Edit the expression or select a bit to flip it.

Expression

text · 8 bits

Every printable ASCII code
Character	Decimal	Hex	Binary
space	32	0x20	00100000
!	33	0x21	00100001
"	34	0x22	00100010
#	35	0x23	00100011
$	36	0x24	00100100
%	37	0x25	00100101
&	38	0x26	00100110
'	39	0x27	00100111
(	40	0x28	00101000
)	41	0x29	00101001
*	42	0x2A	00101010
+	43	0x2B	00101011
,	44	0x2C	00101100
-	45	0x2D	00101101
.	46	0x2E	00101110
/	47	0x2F	00101111
0	48	0x30	00110000
1	49	0x31	00110001
2	50	0x32	00110010
3	51	0x33	00110011
4	52	0x34	00110100
5	53	0x35	00110101
6	54	0x36	00110110
7	55	0x37	00110111
8	56	0x38	00111000
9	57	0x39	00111001
:	58	0x3A	00111010
;	59	0x3B	00111011
<	60	0x3C	00111100
=	61	0x3D	00111101
>	62	0x3E	00111110
?	63	0x3F	00111111
@	64	0x40	01000000
A	65	0x41	01000001
B	66	0x42	01000010
C	67	0x43	01000011
D	68	0x44	01000100
E	69	0x45	01000101
F	70	0x46	01000110
G	71	0x47	01000111
H	72	0x48	01001000
I	73	0x49	01001001
J	74	0x4A	01001010
K	75	0x4B	01001011
L	76	0x4C	01001100
M	77	0x4D	01001101
N	78	0x4E	01001110
O	79	0x4F	01001111
P	80	0x50	01010000
Q	81	0x51	01010001
R	82	0x52	01010010
S	83	0x53	01010011
T	84	0x54	01010100
U	85	0x55	01010101
V	86	0x56	01010110
W	87	0x57	01010111
X	88	0x58	01011000
Y	89	0x59	01011001
Z	90	0x5A	01011010
[	91	0x5B	01011011
\	92	0x5C	01011100
]	93	0x5D	01011101
^	94	0x5E	01011110
_	95	0x5F	01011111
`	96	0x60	01100000
a	97	0x61	01100001
b	98	0x62	01100010
c	99	0x63	01100011
d	100	0x64	01100100
e	101	0x65	01100101
f	102	0x66	01100110
g	103	0x67	01100111
h	104	0x68	01101000
i	105	0x69	01101001
j	106	0x6A	01101010
k	107	0x6B	01101011
l	108	0x6C	01101100
m	109	0x6D	01101101
n	110	0x6E	01101110
o	111	0x6F	01101111
p	112	0x70	01110000
q	113	0x71	01110001
r	114	0x72	01110010
s	115	0x73	01110011
t	116	0x74	01110100
u	117	0x75	01110101
v	118	0x76	01110110
w	119	0x77	01110111
x	120	0x78	01111000
y	121	0x79	01111001
z	122	0x7A	01111010
{	123	0x7B	01111011
\|	124	0x7C	01111100
}	125	0x7D	01111101
~	126	0x7E	01111110

A terminal, a serial monitor and a text file all agree on these codes.

A protocol that sends a command as text depends on the exact code of each letter.

Every later code set keeps these 128 codes. UTF-8 keeps them too.

The blocks are not adjacent. The digits start at 48, the capitals at 65, and the small letters at 97.
The gap between a capital letter and its small form is 32, which is one bit: bit 5.
The code 0 is not the digit 0. The code 0 is a null character.
A code above 127 is outside ASCII. Do not assume a single byte holds one character.

The full editor holds many values, evaluates expressions across them, and reads live values from a serial port.

How many characters does ASCII hold?: ASCII holds 128 codes, from 0 to 127. Of those, 95 are printable.
What is the ASCII code of a space?: A space has the code 32, which is 0x20 and 00100000.
How do I convert a capital letter to a small letter with a bitwise operation?: Apply OR with 0x20 to get the small letter, and AND with 0xDF to get the capital letter.