4. DISPLAY CONTROL

4.1 SCREEN DESCRIPTION

A screen is composed of successive scan lines

gathered in one or several strips. Each strip is

defined by a descriptor stored in memory. A list of

descriptors allows screen composition, different

screens can be defined in memory (see application

note and Figures 13, 14.).

Two kinds of strip are available :

- Uniform color strip

Applications :

- vertical front and back porch

- vertical synchro

- border lines

Parameters :

- number of scan lines

- color

- Character strip

Characters and attributes are defined by a suc-

cession of codes stored in memory; thanks to the

character code, a memory address is calculated

and used to get the character pattern.

Parameters :

- address of the first code

- size, display enable

* U0 is uniform strip number 0, R0 is character strip number 0

DESCRIPTOR LIST

CONTENTS

SCAN LINES

SUM

VERT REGISTER

COMMENTS

VERT REGISTER

COMMENTS

242 Scan Lines (00F0h)

312 Scan Lines (0136h)

U2 Strip is cut (red uniform strip)

U2 (red), U3 (yellow), U4 (cyan) and part of U5 (white) uniform strip are displayed

1460

A8AA

0A02

F8AA 20AB 48AB

D0BA 1402

1906

1903

1907

U0*

U1

R0*

R1

R2

R18

R19

U2

U3

U4

U5

10

10

20

25

25

25

220

230

250

275

300

325

20

10

10

10

10

20

30

40

50

60

Figure 13 : Programmation of Number of Scan Lines - Vertical Register VERT (2FF0/2FF1)

and Descriptor List

OTHER

25th ROW CODES

OTHER

1st ROW CODES

3rd ROW CODES

2nd ROW CODES

OTHER

23th ROW CODES

OTHER

RAM

PAGE CODES LOCATION

UNIF 0

ROW 0

ROW 1

ROW 2

ROW 22

ROW 2

ROW 24

UNIF 1

TOP UNIFORM STRIP

BOTTOM UNIFORM STRIP

1st CHARACTER ROW

2nd CHARACTER ROW

3rd CHARACTER ROW

23th CHARACTER ROW

24th CHARACTER ROW *

25th CHARACTER ROW

Address

of the list

ADDR

REGISTER

RAM

DESCRIPTOR LIST

SCREEN

* Identical to row 2

Figure 14 : Relation between Screen Location/Descriptor Pointer/RAM Page Codes

STV9410

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