Sinclair ZX81 Character Set

Decimal Code	Hexadecimal Code	Character
0	00	(Space)
1	01	block graphic
2	02	block graphic
3	03	block graphic
4	04	block graphic
5	05	block graphic
6	06	block graphic
7	07	block graphic
8	08	block graphic
9	09	block graphic
10	0A	block graphic
The ZX81 has 16 'block graphic' characters which consist of a character square divided into four smaller squares, with every combination of none, one, two, three or four of the small squares 'filled-in', as shown in the top two rows below. These are used by the PLOT and UNPLOT commands to double the effective resolution of the display. The six graphic characters in the bottom row are intended for drawing horizontal bar charts, with the 'chessboard' patterns giving a grey shade. See ZX81 Block Graphics for more details.
11	0B	"
12	0C	£
13	0D	$
14	0E	:
15	0F	?
16	10	(
17	11	)
18	12	>
19	13	<
20	14	=
21	15	+
22	16	-
23	17	*
24	18	/
25	19	;
26	1A	,
27	1B	.
28	1C	0
29	1D	1
30	1E	2
31	1F	3
32	20	4
33	21	5
34	22	6
35	23	7
36	24	8
37	25	9
38	26	A
39	27	B
40	28	C
41	29	D
42	2A	E
43	2B	F
44	2C	G
45	2D	H
46	2E	I
47	2F	J
48	30	K
49	31	L
50	32	M
51	33	N
52	34	O
53	35	P
54	36	Q
55	37	R
56	38	S
57	39	T
58	3A	U
59	3B	V
60	3C	W
61	3D	X
62	3E	Y
63	3F	Z
64	40	RND
65	41	INKEY$
66	42	PI
67	43	not used
68	44	not used
69	45	not used
70	46	not used
71	47	not used
72	48	not used
73	49	not used
74	4A	not used
75	4B	not used
76	4C	not used
77	4D	not used
78	4E	not used
79	4F	not used
80	50	not used
81	51	not used
82	52	not used
83	53	not used
84	54	not used
85	55	not used
86	56	not used
87	57	not used
88	58	not used
89	59	not used
90	5A	not used
91	5B	not used
92	5C	not used
93	5D	not used
94	5E	not used
95	5F	not used
96	60	not used
97	61	not used
98	62	not used
99	63	not used
100	64	not used
101	65	not used
102	66	not used
103	67	not used
104	68	not used
105	69	not used
106	6A	not used
107	6B	not used
108	6C	not used
109	6D	not used
110	6E	not used
111	6F	not used
112	70	cursor up
113	71	cursor down
114	72	cursor left
115	73	cursor right
116	74	GRAPHICS Used when entering program lines after the GRAPHICS key is pressed. Keys then either give the inverse video of their normal character, or a block graphics character.
117	75	EDIT
118	76	NEWLINE      I.e. Enter/Return
119	77	RUBOUT      I.e. Backspace/Delete
120	78	K/L mode
121	79	FUNCTION
122	7A	not used
123	7B	not used
124	7C	not used
125	7D	not used
126	7E	number In ZX81 BASIC program listings, the character form of numerical constants (e.g. 42) is followed, invisibly, by character 126 then the five-byte floating point binary equivalent of the number.
127	7F	cursor
128	80	block graphic
129	81	block graphic
130	82	block graphic
131	83	block graphic
132	84	block graphic
133	85	block graphic
134	86	block graphic
135	87	block graphic
136	88	block graphic
137	89	block graphic
138	8A	block graphic
See after code 10 for the forms of block graphics
139	8B	inverse "
140	8C	inverse £
141	8D	inverse $
142	8E	inverse :
143	8F	inverse ?
144	90	inverse (
145	91	inverse )
146	92	inverse >
147	93	inverse <
148	94	inverse =
149	95	inverse +
150	96	inverse -
151	97	inverse *
152	98	inverse /
153	99	inverse ;
154	9A	inverse ,
155	9B	inverse .
156	9C	inverse 0
157	9D	inverse 1
158	9E	inverse 2
159	9F	inverse 3
160	A0	inverse 4
161	A1	inverse 5
162	A2	inverse 6
163	A3	inverse 7
164	A4	inverse 8
165	A5	inverse 9
166	A6	inverse A
167	A7	inverse B
168	A8	inverse C
169	A9	inverse D
170	AA	inverse E
171	AB	inverse F
172	AC	inverse G
173	AD	inverse H
174	AE	inverse I
175	AF	inverse J
176	B0	inverse K
177	B1	inverse L
178	B2	inverse M
179	B3	inverse N
180	B4	inverse O
181	B5	inverse P
182	B6	inverse Q
183	B7	inverse R
184	B8	inverse S
185	B9	inverse T
186	BA	inverse U
187	BB	inverse V
188	BC	inverse W
189	BD	inverse X
190	BE	inverse Y
191	BF	inverse Z
The ZX81 normally displays black text on a white background. The inverse forms of characters reverse this, i.e. white characters in a black square.
192	C0	"" The double double quote character is used to put a double quote inside a string, which is delimited by normal double quotes. Although it appears as two double quotes in listings it is printed as just one double quote, so that PRINT "ZX81 ""RAM"" pack" would appear as ZX81 "RAM" pack
193	C1	AT
194	C2	TAB
195	C3	not used
196	C4	CODE
197	C5	VAL
198	C6	LEN
199	C7	SIN
200	C8	COS
201	C9	TAN
202	CA	ASN
203	CB	ACS
204	CC	ATN
205	CD	LN
206	CE	EXP
207	CF	INT
208	D0	SQR
209	D1	SGN
210	D2	ABS
211	D3	PEEK
212	D4	USR
213	D5	STR$
214	D6	CHR$
215	D7	NOT
216	D8	**     The 'raise to a power' operator
217	D9	OR
218	DA	AND
219	DB	<=
220	DC	>=
221	DD	<>
The above three comparison operators are treated as single characters. Typing them as two separate characters produces a syntax error.
222	DE	THEN
223	DF	TO
224	E0	STEP
225	E1	LPRINT
226	E2	LLIST
227	E3	STOP
228	E4	SLOW
229	E5	FAST
230	E6	NEW
231	E7	SCROLL
232	E8	CONT
233	E9	DIM
234	EA	REM
235	EB	FOR
236	EC	GOTO
237	ED	GOSUB
238	EE	INPUT
239	EF	LOAD
240	F0	LIST
241	F1	LET
242	F2	PAUSE
243	F3	NEXT
244	F4	POKE
245	F5	PRINT
246	F6	PLOT
247	F7	RUN
248	F8	SAVE
249	F9	RAND
250	FA	IF
251	FB	CLS
252	FC	UNPLOT
253	FD	CLEAR
254	FE	RETURN
255	FF	COPY
Most of the character codes from 193 to 255, plus 64 to 66, are the BASIC keywords. They are stored within the program as a single byte but in listings they are expanded to full words, including a space before and after as necessary to improve readability. The idea of storing BASIC's words as a single byte was carried through from the Sinclair ZX80 and was used because of the very small memory capacity of the unexpanded ZX80 and ZX81. 'PRINT ' would normally take up six bytes whereas character 245 is only one byte.

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