EF9345 datasheet(13/38 Pages) STMICROELECTRONICS

13 / 38 page

Table 2

X and Y

Condition

Physical Address AM(3:10)

987

6543

≥ 8

X5 = 0

X5 = 1

Y<8

Y0 = 0

Y0 = 1

b0 = 0

b0 = 1

SCREEN FORMAT AND ATTRIBUTES

The screen format and attributes are programmed

through 5 indirectly accessible registers : ROR,

TGS, PAT, MAT and DOR. IND command allows

accessing these registers. TGS is also used to

select the timing generator options (see Table 3).

Row and Character Code Format

PAT7 ; TGS(6:7)

Two row formats and 5 character code formats are

available but cannot be mixed in a given screen.

DOR register interpretation is completely row for-

mat dependentand is discussed in the correspond-

nig 40 char/row and 80 char/row section.

Screen Partition - Page Pointer ROR

(See Table 3)

The screen is partitioned into 3 areas :

- The margin,

- The service row,

- The bulk of remaining rows.

MAT(0:3) declares the color of the margin and the

value IM of its insert attribute.

ROR register points to the page to be displayed and

gives the 3 MSB’s of the Z address : Z0 =0

implicitly ; the page block address must be even.

YOR gives the first row buffers to be displayed at

the top of the bulk area. The next row buffers to be

displayed are fetched sequentially by incrementing

the Y address (modulo 24). This address never

gets out of the origin block. Incrementation of YOR

by the microprocessor yields a roll up.

Service Row : TGS5 - PAT0

The service row is displayed for 10 TV lines on top

of the screen and does not roll. Following TGS5,it

is fetched from the origin block at either Y = 0 or Y

= 1. The Y = 1 is a partial row buffer. It can be used

only with variable 40 char./row and an 8 byte

attribute file. The service row may be disabled by

PAT0 = 0 ; it is the displayed as a margin extension.

BULK : TGS0 ; PAT(1:2) ; MAT7

It is displayed after the service row for 200 or 240

TV lines according to TGS0. Each row buffer is

usually displayed for 10 TV lines. However,

MAT7 = 1 doubles this figure. Then every character

appears in double height (double height characters

are quadrupled).

PAT1 = 0 and/or PAT2 = 0 disables respectively the

upper 120 lines and/or the lower 80/120 lines of the

bulk.

When disabled, the corresponding TV lines are

displayed as a margin extension.

Cursor MAT(4:6)

To be displayed with the cursor attributes, a char-

acter must be pointed by the main pointer (R6, R7)

and MAT6 must be set. The cursor attributes are

given by MAT(4:5) :

- Complementation : the R, G and B of each pixel

is logically negated.

R, G, B

→ R, G, B

- Underline : the underline attribute of this charac-

ter is negated.

- Flash : the character is periodically displayed

with, then without, its cursor attributes (50% /

50% ;

≈1Hz).

Flash Enable (PAT6) - Conceal Enable (PAT3)

Any character flashing attribute is a ”don’t care”

when PAT6 = 0. When PAT6=1, a character flashes

if its flashing attribute is set. It is then periodically

displayed as a space (50% / 50% ; 0.5Hz).

PAT3 is a ”don’t care” for 80 char./row formats.

When any 40 char./row format is in use :

-If PAT3 = 0 the conceal attribute of any character

is a don’t care

-If PAT3 = 1, the conceal attribute of each charac-

ter is interpreted : a concealed character appears

as a space on the screen.

EF9345

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