As we saw at SDLSTL (560), the display list is actually a little program for ANTIC, telling it what the screen is to look like. It has its own special commands, as summarized in Figure 63. To use this chart, decide which of the HSC, VSC, LMS, and DLI options you want (see SDLSTL for a description of each), find the column that has the corresponding boxes LABELED in at the top, and then follow it down to the instruction you want.

Since this is a chart that assembly language programmers are going to use a lot, I'll also include a hexadecimal version (Figure 64).

			HSC		HSC		HSC		HSC		HSC		HSC		HSC	HSC
				VSC	VSC			VSC	VSC			VSC	VSC			VSC	VSC
						LMS	LMS	LMS	LMS					LMS	LMS	LMS	LMS
										DLI	DLI	DLI	DLI	DLI	DLI	DLI	DLI
BLK	1	0								128
BLK	2	16								144
BLK	3	32								160
BLK	4	48								176
BLK	5	64								192
BLK	6	80								208
BLK	7	96								224
BLK	8	112								240
JMP		1								129
JVB		65								193
CHR	2	2	18	34	50	66	82	98	114	130	146	162	178	194	210	226	242
CHR	3	3	19	35	51	67	83	99	115	131	147	163	179	195	211	227	243
CHR	4	4	20	36	52	68	84	100	116	132	148	164	180	196	212	228	244
CHR	5	5	21	37	53	69	85	101	117	133	149	165	181	197	213	229	245
CHR	6	6	22	38	54	70	86	102	118	134	150	166	182	198	214	230	246
CHR	7	7	23	39	55	71	87	103	119	135	151	167	183	199	215	231	247
MAP	8	8	24	40	56	72	88	104	120	136	152	168	184	200	216	232	248
MAP	9	9	25	41	57	73	89	105	121	137	153	169	185	201	217	233	249
MAP	10	10	26	42	58	74	90	106	122	138	154	170	186	202	218	234	250
MAP	11	11	27	43	59	75	91	107	123	139	155	171	187	203	219	235	251
MAP	12	12	28	44	60	76	92	108	124	140	156	172	188	204	220	236	252
MAP	13	13	29	45	61	77	93	109	125	141	157	173	189	205	221	237	253
MAP	14	14	30	46	62	78	94	110	126	142	158	174	190	206	222	238	254
MAP	15	15	31	47	63	79	95	111	127	143	159	175	191	207	223	239	255

            FIGURE 63. Display list command chart

HSC

HSC

HSC

HSC

HSC

HSC

HSC

HSC

VSC

VSC

VSC

VSC

VSC

VSC

VSC

VSC

LMS

LMS

LMS

LMS

LMS

LMS

LMS

LMS

DLI

DLI

DLI

DLI

DLI

DLI

DLI

DLI

BLK

1

00

80

BLK

2

10

90

BLK

3

20

A0

BLK

4

30

B0

BLK

5

40

C0

BLK

6

50

D0

BLK

7

60

E0

BLK

8

70

F0

JMP

01

81

JVB

41

C1

CHR

2

02

12

22

32

42

52

62

72

82

92

A2

B2

C2

D2

E2

F2

CHR

3

03

13

23

33

43

53

63

73

83

93

A3

B3

C3

D3

E3

F3

CHR

4

04

14

24

34

44

54

64

74

84

94

A4

B4

C4

D4

D4

F4

CHR

5

05

15

25

35

45

55

65

75

85

95

A5

B5

C5

D5

E5

F5

CHR

6

06

16

26

36

46

56

66

76

86

96

A6

B6

C6

D6

E6

F6

CHR

7

07

17

27

37

47

57

67

77

87

97

A7

B7

C7

D7

E7

F7

MAP

8

08

18

28

38

48

58

68

78

88

98

A8

B8

C8

D8

E8

F8

MAP

9

09

19

29

39

49

59

69

79

89

99

A9

B9

C9

D9

E9

F9

MAP

A

0A

1A

2A

3A

4A

5A

6A

7A

8A

9A

AA

BA

CA

DA

EA

FA

MAP

B

0B

1B

2B

3B

4B

5B

6B

7B

8B

9B

AB

BB

CB

DB

EB

FB

MAP

C

0C

1C

2C

3C

4C

5C

6C

7C

8C

9C

AC

BC

CC

DC

EC

FC

MAP

D

0D

1D

2D

3D

4D

5D

6D

7D

8D

9D

AD

BD

CD

DD

ED

FD

MAP

E

0E

1E

2E

3E

4E

5E

6E

7E

8E

9E

AE

BE

CE

DE

EE

FE

MAP

F

0F

1F

2F

3F

4F

5F

6F

7F

8F

9F

AF

BF

CF

DF

EF

FF

        FIGURE 64. Display list command chart, hex version


Let's take a look now at the various CHR and MAP modes:

CHR 2 is GRAPHICS 0.

CHR 3 is the same as GRAPHICS 0 except that the characters are 10-scan-lines high instead of 8. This allows you to have lowercase descenders, which means that the tails on "g", "j", "p", "q", and "y" can drop below the rest of the letters as they should. How do you use this mode? The first step is to redefine the character set. Actually, you only have to change the lowercase letters. What will happen is ANTIC will take the first two bytes of the character description and stick them on the end of the character. It will then make the first two scan lines of the character blank. For nonlowercase characters, it will leave the bytes in order and make the last two scan lines blank. Just in case that doesn't make any sense, let's look at it in pictures (Figure 65).

		In memory:
	00000000		00001100
	01100110		01111000
	01100110		00000000
	01100110		01100110
	00111100		01100110
	00011000		01100110
	00011000		01100110
	00011000		00111110
		On the screen:
(0)	##  ##
(1)	##  ##
(2)	##  ##
(3)	####		##  ##
(4)	##		##  ##
(5)	##		##  ##
(6)	##		##  ##
(7)			#####
(8)			##
(9)			####

        FIGURE 65. Scan lines with lower-case letters

You should note that because each character is now 10-scan-lines high, you can only have 19 rows on the screen (192/10). Make sure of this when you change the display list.

CHR 4 lets you have multi-colored characters. That's right, you can have as many as four different colors in the same character. Let's take a look at how this works.

ANTIC mode four characters are the same size as graphics mode zero characters. The difference, however, is in the size of the pixels that make up the character. The pixels in both modes are one scan line high, but in ANTIC mode four they are as wide as graphics mode seven pixels (one color clock) rather than graphics mode eight. Why? In order to have four colors, a pixel must be represented by at least two bits. That means that the ANTIC mode four pixels have to be twice as wide as those in graphics mode zero, which use one-bit-per-pixel.

Because a character in ANTIC mode four is only four by eight pixels, they aren't of much use for letters and stuff. They are, however, great for graphics. Whatever you end up using them for, How ANTIC interprets a character description byte in this mode is shown in Figure 66.

Now you may be wondering what happens if you try and print a character in inverse video (i.e., an ATASCII value greater than 127). Do all the colors reverse? No, only the pixels with a value of "11" will change; Instead of getting their color from COLOR2 they will get it from COLORS. This means that you can have all five colors at the same time!

To design a character set for this mode, just follow the instructions given for a regular character set, keeping the preceding changes in mind.

BITS	7         6	5         4	3         2	1        0
USE	PIXEL 1	PIXEL 2	PIXEL 3	PIXEL 4
PIXEL VALUE	COLOR REGISTER
00	COLOR4 (background)
01	COLOR0
10	COLOR1
11	COLOR2

            FIGURE 66. Character description via ANTIC


CHR 5 is the same as CHR 4 except the characters are now twice as high. Otherwise there's no difference.

CHR 6 is GRAPHICS 1.

CHR 7 is GRAPHICS 2.

MAP 8 is GRAPHICS 3.

MAP 9 is GRAPHICS 4.

MAP 10 is GRAPHICS 5.

MAP 11 is GRAPHICS 6.

MAP 12 is the same as MAP l l except the pixels are one scan line high instead of two.

MAP 13 is GRAPHICS 7.

MAP 14 is the same as MAP 13 except the pixels are one scan line high instead of two. See DINDEX at location 87 for an example of this mode.

MAP 15 is GRAPHICS 8.

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