tilascii table

The ASCII 7-bit character encoding is ubiquitous¹ and foundational to how computers talk to each other. It has an absolutely fascinating history that dates surprisingly far back. The ASCII standard started in 1963, and was iterated until 1986. ASCII was based on ITA2, a telegraph standard from 1924, which itself derived from Baudot code from 1870—literally the beginning of digital communication (the namesake for “baud” speed).

0x00
0x10
0x20
0x30
0x40
0x50
0x60
0x70
0x00
␀ ⌃@ \0
␐ ⌃P
Space
0
@
P
`
p
0x01
␁ ⌃A
␑ ⌃Q
!
1
A
Q
a
q
0x02
␂ ⌃B
␒ ⌃R
"
2
B
R
b
r
0x03
␃ ⌃C
␓ ⌃S
#
3
C
S
c
s
0x04
␄ ⌃D
␔ ⌃T
$
4
D
T
d
t
0x05
␅ ⌃E
␕ ⌃U
%
5
E
U
e
u
0x06
␆ ⌃F
␖ ⌃V
&
6
F
V
f
v
0x07
␇ ⌃G \a
␗ ⌃W
'
7
G
W
g
w
0x08
␈ ⌃H \b
␘ ⌃X
(
8
H
X
h
x
0x09
␉ ⌃I \t
␙ ⌃Y
)
9
I
Y
i
y
0x0A
␊ ⌃J \n
␚ ⌃Z
*
:
J
Z
j
z
0x0B
␋ ⌃K \v
␛ ⌃[ \e
+
;
K
[
k
{
0x0C
␌ ⌃L \f
␜ ⌃\
,
<
L
\
l
|
0x0D
␍ ⌃M \r
␝ ⌃]
-
=
M
]
m
}
0x0E
␎ ⌃N
␞ ⌃^
.
>
N
^
n
~
0x0F
␏ ⌃O
␟ ⌃_
/
?
O
_
o
␡ ⌃?

Other fun facts about ASCII:

• The first 128 Unicode values are ASCII. UTF-8, the most common modern encoding, uses a variable number of bytes to cover the full Unicode spectrum, but just happens to use exactly one byte for the first 128 and exactly matches ASCII. That means every ancient ASCII file is also a valid modern UTF-8 file. This is a beautiful hack and a major reason for the success of UTF-8.

• The number digits are carefully placed so BCD can be converted to ASCII and vice-versa in one instruction: ascii = bcd XOR 0x30.

• Many keys you still reach via “shift” on a modern keyboard are either 0x10 or 0x20 above their standard key, a holdover from mechanical typewriters.

• Lowercase letters are exactly 0x20 above uppercase.

• Your “control” key has a ⌃ on it because its original purpose was to remap typical keys to control keys by xor’ing the highest bit 0x40 (XOR also happens to be ^ in C). Some of these vestiges of the past still work everywhere, and all should work in your terminal! Try ⌃H for a home-row oriented backspace.