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Alt code

Input method

On personal computers with numeric keypads that use Microsoft operating systems, such as Windows, many characters that do not have a dedicated key combination on the keyboard may nevertheless be entered using the Alt code (the Alt numpad input method). This is done by pressing and holding the key, then typing a number on the keyboard's numeric keypad that identifies the character and then releasing .

MS-DOS

On IBM PC compatible personal computers from the 1980s, the BIOS allowed the user to hold down the key and type a decimal number on the keypad. It would place the corresponding code into the keyboard buffer so that it would look (almost) as if the code had been entered by a single keystroke. Applications reading keystrokes from the BIOS would behave according to what action they associate with that code. Some would interpret the code as a command, but often it would be interpreted as an 8-bit character from the current code page that was inserted into the text the user was typing. On the original IBM PC the code page was CP437.

Some Eastern European, Arabic and Asian computers used other hardware code pages, and MS-DOS was able to switch between them at runtime with commands like KEYB, CHCP or MODE. This causes the Alt combinations to produce different characters (as well as changing the display of any previously-entered text in the same manner). A common choice in locales using variants of the Latin alphabet was CP850, which provided more Latin character variants. (There were, however, many more code pages).

PC keyboards designed for non-English use included other methods of inserting these characters, such as national keyboard layouts, the AltGr key or dead keys, but the Alt key was the only method of inserting some characters, and the only method that was the same on all machines, so it remained very popular. This input method is emulated by many pieces of software (such as later versions of MS-DOS and Windows) that do not use the BIOS keyboard decoding.

In the ASCII standard, the numbers 0-31 and 127 are assigned to control characters, for instance, code point 7 is typed by . While some (most?) applications would insert a bullet character (code point 7 on code page 437), some would treat this identical to which often was a command for the program.

Windows

The Alt codes had become so well known and memorized by users that Microsoft decided to preserve them in Microsoft Windows, even though the OS features a newer and different set of code pages such as CP1252. Windows includes the following processing algorithm for Alt code, which supports both methods:

The familiar + combination retains the old MS-DOS behavior, i.e., generates characters from the legacy code pages now called "OEM code pages". For instance + produces . code point 163 in CP437 or CP850. The "OEM code page" selection served little or no other purpose other than to control what Alt codes produced, if other code pages were selected then these numbers could produce different characters, but it did not change the display. It was impossible to type characters that were not in the Windows code page, such as box-drawing symbols.
The new + combination (which prefixes a zero to each Alt code), produces characters from the newer "ANSI code pages". For instance + results in (when CP1252 is active, because it occupies position 163 in that code page). The active Windows code page could be different, which could change the effect of these Alt codes.

Unicode

Later versions of Windows and applications such as Microsoft Word supported Unicode. As Unicode included all the characters in all the MSDOS code pages, this had the immediate benefit that all the old MSDOS Alt combinations worked, not just the ones that existed in the Windows Code Page. And far more software stopped changing how documents displayed or printed when the selected code page was changed.

In the IBM PC Bios typing an Alt code greater than 255 produced the same as that number modulo 256. Some applications retained this behavior, while others (in particular applications using the Windows RichEdit control, such as WordPad and PSPad) made numbers from 256 to 65,535 produce the corresponding Unicode character. For instance, + in WordPad produces the . If the Windows Code Page was set to CP1252 then all Unicode BMP characters except control characters could be typed this way.

Hex Alt Codes

Because most Unicode documentation and character tables show the code points in hex, not decimal, a variation of Alt codes was developed to allow the typing of numbers in hex (using the main keyboard for –). To enable it, a user must set or create a string type () value called EnableHexNumpad in the registry key HKEY_CURRENT_USER\Control Panel\Input Method, assign the value data 1 to it, and then reboot or log out/in. A leading then indicates hex input, for example will produce (e with caron).

There are many other ways of typing arbitrary Unicode characters, such as the Character Map utility.

Other operating systems

The Alt key method does not work on ChromeOS, macOS, Linux or other operating systems and there is no evidence of interest in replicating it. However, numeric entry of Unicode characters is possible in most Unix or Unix-like OSs by pressing and releasing , and typing the hex number followed by the space bar or enter key. For example,

For the registered trademark symbol , type , , .
For the no entry sign , type , , .

Limitations

If is disabled, attempting an Alt code may cause unexpected results in some applications, due to the controls used on the same key. For example, can be taken as , causing a web browser to go back one page.

List of codes

Unicode	CP437	CP850	CP1252	Unicode name
U+00A0	255	0160	NO-BREAK SPACE
U+00A1	173	0161	INVERTED EXCLAMATION MARK
U+00A2	155	189	0162	CENT SIGN
U+00A3	156	0163	POUND SIGN
U+00A4		207	0164	CURRENCY SIGN
U+00A5	157	190	0165	YEN SIGN
U+00A6		221	0166	BROKEN BAR
U+00A7	21	245	0167	SECTION SIGN
U+00A8		249	0168	DIAERESIS
U+00A9		184	0169	COPYRIGHT SIGN
U+00AA	166	0170	FEMININE ORDINAL INDICATOR
U+00AB	174	0171	LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
U+00AC	170	0172	NOT SIGN
U+00AD		240	0173	SOFT HYPHEN
U+00AE		169	0174	REGISTERED SIGN
U+00AF		238	0175	MACRON
U+00B0	248	0176	DEGREE SIGN
U+00B1	241	0177	PLUS-MINUS SIGN
U+00B2	253	0178	SUPERSCRIPT TWO
U+00B3		252	0179	SUPERSCRIPT THREE
U+00B4		239	0180	ACUTE ACCENT
U+00B5	230	0181	MICRO SIGN
U+00B6	20	244	0182	PILCROW SIGN
U+00B7	250	0183	MIDDLE DOT
U+00B8		247	0184	CEDILLA
U+00B9		251	0185	SUPERSCRIPT ONE
U+00BA	167	0186	MASCULINE ORDINAL INDICATOR
U+00BB	175	0187	RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
U+00BC	172	0188	VULGAR FRACTION ONE QUARTER
U+00BD	171	0189	VULGAR FRACTION ONE HALF
U+00BE		243	0190	VULGAR FRACTION THREE QUARTERS
U+00BF	168	0191	INVERTED QUESTION MARK
U+00C0		183	0192	LATIN CAPITAL LETTER A WITH GRAVE
U+00C1	181	0193	LATIN CAPITAL LETTER A WITH ACUTE
U+00C2		182	0194	LATIN CAPITAL LETTER A WITH CIRCUMFLEX
U+00C3		199	0195	LATIN CAPITAL LETTER A WITH TILDE
U+00C4	142	0196	LATIN CAPITAL LETTER A WITH DIAERESIS
U+00C5	143	0197	LATIN CAPITAL LETTER A WITH RING ABOVE
U+00C6	146	0198	LATIN CAPITAL LETTER AE
U+00C7	128	0199	LATIN CAPITAL LETTER C WITH CEDILLA
U+00C8		212	0200	LATIN CAPITAL LETTER E WITH GRAVE
U+00C9	144	0201	LATIN CAPITAL LETTER E WITH ACUTE
U+00CA		210	0202	LATIN CAPITAL LETTER E WITH CIRCUMFLEX
U+00CB		211	0203	LATIN CAPITAL LETTER E WITH DIAERESIS
U+00CC		222	0204	LATIN CAPITAL LETTER I WITH GRAVE
U+00CD		214	0205	LATIN CAPITAL LETTER I WITH ACUTE
U+00CE		215	0206	LATIN CAPITAL LETTER I WITH CIRCUMFLEX
U+00CF		216	0207	LATIN CAPITAL LETTER I WITH DIAERESIS
U+00D0		209	0208	LATIN CAPITAL LETTER ETH
U+00D1	165	0209	LATIN CAPITAL LETTER N WITH TILDE
U+00D2		227	0210	LATIN CAPITAL LETTER O WITH GRAVE
U+00D3		224	0211	LATIN CAPITAL LETTER O WITH ACUTE
U+00D4		226	0212	LATIN CAPITAL LETTER O WITH CIRCUMFLEX
U+00D5		229	0213	LATIN CAPITAL LETTER O WITH TILDE
U+00D6	153	0214	LATIN CAPITAL LETTER O WITH DIAERESIS
U+00D7		158	0215	MULTIPLICATION SIGN
U+00D8		157	0216	LATIN CAPITAL LETTER O WITH STROKE
U+00D9		235	0217	LATIN CAPITAL LETTER U WITH GRAVE
U+00DA		233	0218	LATIN CAPITAL LETTER U WITH ACUTE
U+00DB		234	0219	LATIN CAPITAL LETTER U WITH CIRCUMFLEX
U+00DC	154	0220	LATIN CAPITAL LETTER U WITH DIAERESIS
U+00DD		237	0221	LATIN CAPITAL LETTER Y WITH ACUTE
U+00DE		232	0222	LATIN CAPITAL LETTER THORN
U+00DF	225	0223	LATIN SMALL LETTER SHARP S
U+00E0	133	0224	LATIN SMALL LETTER A WITH GRAVE
U+00E1	160	0225	LATIN SMALL LETTER A WITH ACUTE
U+00E2	131	0226	LATIN SMALL LETTER A WITH CIRCUMFLEX
U+00E3		198	0227	LATIN SMALL LETTER A WITH TILDE
U+00E4	132	0228	LATIN SMALL LETTER A WITH DIAERESIS
U+00E5	134	0229	LATIN SMALL LETTER A WITH RING ABOVE
U+00E6	145	0230	LATIN SMALL LETTER AE
U+00E7	135	0231	LATIN SMALL LETTER C WITH CEDILLA
U+00E8	138	0232	LATIN SMALL LETTER E WITH GRAVE
U+00E9	130	0233	LATIN SMALL LETTER E WITH ACUTE
U+00EA	136	0234	LATIN SMALL LETTER E WITH CIRCUMFLEX
U+00EB	137	0235	LATIN SMALL LETTER E WITH DIAERESIS
U+00EC	141	0236	LATIN SMALL LETTER I WITH GRAVE
U+00ED	161	0237	LATIN SMALL LETTER I WITH ACUTE
U+00EE	140	0238	LATIN SMALL LETTER I WITH CIRCUMFLEX
U+00EF	139	0239	LATIN SMALL LETTER I WITH DIAERESIS
U+00F0		208	0240	LATIN SMALL LETTER ETH
U+00F1	164	0241	LATIN SMALL LETTER N WITH TILDE
U+00F2	149	0242	LATIN SMALL LETTER O WITH GRAVE
U+00F3	162	0243	LATIN SMALL LETTER O WITH ACUTE
U+00F4	147	0244	LATIN SMALL LETTER O WITH CIRCUMFLEX
U+00F5		228	0245	LATIN SMALL LETTER O WITH TILDE
U+00F6	148	0246	LATIN SMALL LETTER O WITH DIAERESIS
U+00F7	246	0247	DIVISION SIGN
U+00F8		155	0248	LATIN SMALL LETTER O WITH STROKE
U+00F9	151	0249	LATIN SMALL LETTER U WITH GRAVE
U+00FA	163	0250	LATIN SMALL LETTER U WITH ACUTE
U+00FB	150	0251	LATIN SMALL LETTER U WITH CIRCUMFLEX
U+00FC	129	0252	LATIN SMALL LETTER U WITH DIAERESIS
U+00FD		236	0253	LATIN SMALL LETTER Y WITH ACUTE
U+00FE		231	0254	LATIN SMALL LETTER THORN
U+00FF	152	0255	LATIN SMALL LETTER Y WITH DIAERESIS
U+0131		213		LATIN SMALL LETTER DOTLESS I
U+0152	}}	0140	LATIN CAPITAL LIGATURE OE
U+0153	}}	0156	LATIN SMALL LIGATURE OE
U+0160	}}	0138	LATIN CAPITAL LETTER S WITH CARON
U+0161	}}	0154	LATIN SMALL LETTER S WITH CARON
U+0178	}}	0159	LATIN CAPITAL LETTER Y WITH DIAERESIS
U+017D	}}	0142	LATIN CAPITAL LETTER Z WITH CARON
U+017E	}}	0158	LATIN SMALL LETTER Z WITH CARON
U+0192	159	0131	LATIN SMALL LETTER F WITH HOOK
U+02C6	}}	0136	MODIFIER LETTER CIRCUMFLEX ACCENT
U+02DC	}}	0152	SMALL TILDE
U+0393	226	}}	GREEK CAPITAL LETTER GAMMA
U+0398	233	}}	GREEK CAPITAL LETTER THETA
U+03A3	228	}}	GREEK CAPITAL LETTER SIGMA
U+03A6	232	}}	GREEK CAPITAL LETTER PHI
U+03A9	234	}}	GREEK CAPITAL LETTER OMEGA
U+03B1	224	}}	GREEK SMALL LETTER ALPHA
U+03B4	235	}}	GREEK SMALL LETTER DELTA
U+03B5	238	}}	GREEK SMALL LETTER EPSILON
U+03C0	227	}}	GREEK SMALL LETTER PI
U+03C3	229	}}	GREEK SMALL LETTER SIGMA
U+03C4	231	}}	GREEK SMALL LETTER TAU
U+03C6	237	}}	GREEK SMALL LETTER PHI
U+2013	}}	0150	EN DASH
U+2014	}}	0151	EM DASH
U+2017		242		DOUBLE LOW LINE
U+2018	}}	0145	LEFT SINGLE QUOTATION MARK
U+2019	}}	0146	RIGHT SINGLE QUOTATION MARK
U+201A	}}	0130	SINGLE LOW-9 QUOTATION MARK
U+201C	}}	0147	LEFT DOUBLE QUOTATION MARK
U+201D	}}	0148	RIGHT DOUBLE QUOTATION MARK
U+201E	}}	0132	DOUBLE LOW-9 QUOTATION MARK
U+2020	}}	0134	DAGGER
U+2021	}}	0135	DOUBLE DAGGER
U+2022	7	0149	BULLET
U+2026	}}	0133	HORIZONTAL ELLIPSIS
U+2030	}}	0137	PER MILLE SIGN
U+2039	}}	0139	SINGLE LEFT-POINTING ANGLE QUOTATION MARK
U+203A	}}	0155	SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
U+203C	19		DOUBLE EXCLAMATION MARK
U+207F	252	}}	SUPERSCRIPT LATIN SMALL LETTER N
U+20A7	158	}}	PESETA SIGN
U+20AC	}}	0128	EURO SIGN
U+2122	}}	0153	TRADE MARK SIGN
U+2190	27		LEFTWARDS ARROW
U+2191	24		UPWARDS ARROW
U+2192	26		RIGHTWARDS ARROW
U+2193	25		DOWNWARDS ARROW
U+2194	29		LEFT RIGHT ARROW
U+2195	18		UP DOWN ARROW
U+21A8	23		UP DOWN ARROW WITH BASE
U+2219	249	}}	BULLET OPERATOR
U+221A	251	}}	SQUARE ROOT
U+221E	236	}}	INFINITY
U+221F	28		RIGHT ANGLE
U+2229	239	}}	INTERSECTION
U+2248	247	}}	ALMOST EQUAL TO
U+2264	243	}}	LESS-THAN OR EQUAL TO
U+2261	240	}}	IDENTICAL TO
U+2265	242	}}	GREATER-THAN OR EQUAL TO
U+2302	127		HOUSE
U+2310	169	}}	REVERSED NOT SIGN
U+2320	244	}}	TOP HALF INTEGRAL
U+2321	245	}}	BOTTOM HALF INTEGRAL
U+2500	196		BOX DRAWINGS LIGHT HORIZONTAL
U+2502	179		BOX DRAWINGS LIGHT VERTICAL
U+250C	218		BOX DRAWINGS LIGHT DOWN AND RIGHT
U+2510	191		BOX DRAWINGS LIGHT DOWN AND LEFT
U+2514	192		BOX DRAWINGS LIGHT UP AND RIGHT
U+2518	217		BOX DRAWINGS LIGHT UP AND LEFT
U+251C	195		BOX DRAWINGS LIGHT VERTICAL AND RIGHT
U+2524	180		BOX DRAWINGS LIGHT VERTICAL AND LEFT
U+252C	194		BOX DRAWINGS LIGHT DOWN AND HORIZONTAL
U+2534	193		BOX DRAWINGS LIGHT UP AND HORIZONTAL
U+253C	197		BOX DRAWINGS LIGHT VERTICAL AND HORIZONTAL
U+2550	205		BOX DRAWINGS DOUBLE HORIZONTAL
U+2551	186		BOX DRAWINGS DOUBLE VERTICAL
U+2552	213	}}	BOX DRAWINGS DOWN SINGLE AND RIGHT DOUBLE
U+2553	214	}}	BOX DRAWINGS DOWN DOUBLE AND RIGHT SINGLE
U+2554	201		BOX DRAWINGS DOUBLE DOWN AND RIGHT
U+2555	184	}}	BOX DRAWINGS DOWN SINGLE AND LEFT DOUBLE
U+2556	183	}}	BOX DRAWINGS DOWN DOUBLE AND LEFT SINGLE
U+2557	187		BOX DRAWINGS DOUBLE DOWN AND LEFT
U+2558	212	}}	BOX DRAWINGS UP SINGLE AND RIGHT DOUBLE
U+2559	211	}}	BOX DRAWINGS UP DOUBLE AND RIGHT SINGLE
U+255A	200		BOX DRAWINGS DOUBLE UP AND RIGHT
U+255B	190	}}	BOX DRAWINGS UP SINGLE AND LEFT DOUBLE
U+255C	189	}}	BOX DRAWINGS UP DOUBLE AND LEFT SINGLE
U+255D	188		BOX DRAWINGS DOUBLE UP AND LEFT
U+255E	198	}}	BOX DRAWINGS VERTICAL SINGLE AND RIGHT DOUBLE
U+255F	199	}}	BOX DRAWINGS VERTICAL DOUBLE AND RIGHT SINGLE
U+2560	204		BOX DRAWINGS DOUBLE VERTICAL AND RIGHT
U+2562	182	}}	BOX DRAWINGS VERTICAL DOUBLE AND LEFT SINGLE
U+2563	185		BOX DRAWINGS DOUBLE VERTICAL AND LEFT
U+2564	209	}}	BOX DRAWINGS DOWN SINGLE AND HORIZONTAL DOUBLE
U+2565	210	}}	BOX DRAWINGS DOWN DOUBLE AND HORIZONTAL SINGLE
U+2566	203		BOX DRAWINGS DOUBLE DOWN AND HORIZONTAL
U+2567	207	}}	BOX DRAWINGS UP SINGLE AND HORIZONTAL DOUBLE
U+2568	208	}}	BOX DRAWINGS UP DOUBLE AND HORIZONTAL SINGLE
U+2569	202		BOX DRAWINGS DOUBLE UP AND HORIZONTAL
U+256A	216	}}	BOX DRAWINGS VERTICAL SINGLE AND HORIZONTAL DOUBLE
U+256B	215	}}	BOX DRAWINGS VERTICAL DOUBLE AND HORIZONTAL SINGLE
U+256C	206		BOX DRAWINGS DOUBLE VERTICAL AND HORIZONTAL
U+2580	223		UPPER HALF BLOCK
U+2584	220		LOWER HALF BLOCK
U+2588	219		FULL BLOCK
U+258C	221	}}	LEFT HALF BLOCK
U+2590	222	}}	RIGHT HALF BLOCK
U+2591	176		LIGHT SHADE
U+2592	177		MEDIUM SHADE
U+2593	178		DARK SHADE
U+25A0	254		BLACK SQUARE
U+25AC	22		BLACK RECTANGLE
U+25B2	30		BLACK UP-POINTING TRIANGLE
U+25BA	16		BLACK RIGHT-POINTING POINTER
U+25BC	31		BLACK DOWN-POINTING TRIANGLE
U+25C4	17		BLACK LEFT-POINTING POINTER
U+25CB	9		WHITE CIRCLE
U+25D8	8		INVERSE BULLET
U+25D9	10		INVERSE WHITE CIRCLE
U+263A	1		WHITE SMILING FACE
U+263B	2		BLACK SMILING FACE
U+263C	15		WHITE SUN WITH RAYS
U+2640	12		FEMALE SIGN
U+2642	11		MALE SIGN
U+2660	6		BLACK SPADE SUIT
U+2663	5		BLACK CLUB SUIT
U+2665	3		BLACK HEART SUIT
U+2666	4		BLACK DIAMOND SUIT
U+266A	13		EIGHTH NOTE
U+266B	14		BEAMED EIGHTH NOTES

Notes

References

de:Alt (Taste)#Alt-Code

References

"Alt Codes List of Alt Key Codes Symbols".
If the entered value exceeds 255, only the remainder after dividing by 256 (i.e., the value [[modulo]] 256) was used by the BIOS. For example, 520 is interpreted as 520 mod 256 = 8, so it produces the same character as for value 8.
(2016-07-22). "To input characters that are not on your keyboard".
Chen, Raymond. (2 July 2024). "The history of Alt+number sequences, and why Alt+9731 sometimes gives you a heart and sometimes a snowman". Microsoft.
Walker, Jim. (27 April 2022). "About Rich Edit Controls". Microsoft.

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