EF9345 datasheet(10/38 Pages) STMICROELECTRONICS

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FUNCTIONAL DESCRIPTION

The EF9345 is a low cost, semigraphic, CRT con-

troller.

It is optimized for use with a low cost, monochrome

or color TV type CRT (64ms per line, 50 or 60Hz

refresh frequency).

The EF9345 displays up to 25 rows of 40 charac-

ters or 25 rows of 80 characters.

The on-chip character generator provides a 128

standard, 5 x 7, character set and standard semi-

graphic sets.

More use definable (8 x 10) alphanumeric or semi-

graphic sets may be mapped in the 16 K x 8 private

memory addressing space.

These user definable sets are available only in 40

characters per row format.

Microprocessor Interface

The EF9345 provides an 8-bit, adress/data multi-

plexed microprocessor interface.

It is directly compatible with popular (6801, 8048,

8051, 8035, ...) microprocessors.

Registers

The microprocessor directly accesses 8 registers :

- R0 : Command/status register.

- R1, R2, R3 : Data registers.

- R4, R5, R6, R7 : Each of these register pairs

points into the private memory.

Through these registers, the microprocessor indi-

rectly accesses the private memory and 5 more

registers :

- ROR, DOR : Base address of displayed page

memory and used external character generators.

- PAT, MAT, TGS : Used to select the page attrib-

utes and format, and to program the timing gen-

erator option.

Private Memory

The user may partition the 16 K x 8 private memory

addressing space between :

- Page of character codes (2 K x 8 or 3 K x 8),

- External character generators,

- General purpose user area.

Many types of memory components are suitable :

- ROM, DRAM or SRAM,

- 2 K x 8, 8 K x 8, 16 K x 4 organizations,

- Modest 500ns cycle time and 250ns access time

is required.

40 Characters per Row : Character Code

Formats and Attributes

Once the 40 characters per row format has been

selected, one character code format out of three

must be chosen :

- 24-bit fixed format :

All the attributes are provided in parallel.

- 8/24-bit compressed format :

All the attributes are latched.

- 16-bit fixed format :

Some parallel attributes, other are latched.

Character attributes provided :

- Background and foreground color (3 bits each),

- Double height, double width,

- Blinking,

- Reverse,

- Underlining,

- Conceal,

- Insert,

- Accentuation of lower case characters,

- 3 x 100 user definable character generator in

memory,

- 8 x 100 semi-graphic quadrichrome characters.

80 Characters per Row Format : Character

Code Format and Attributes

Two character code formats are provided :

- Long (12 bits) with 4 parallel attributes :

• Blinking,

• Underlining,

• Reverse,

• Color select.

- Short (8 bits) : no attributes.

Timing Generator

The whole timing is derived from a 12MHz main

clock input.

The RGB outputs are shifted at 8MHz for the 40

character/row format and at 12MHz for the 80

character/row.

Besides, the user may select :

- 50Hz or 60Hz vertical sync. frequency,

- Interlaced or not,

- Separated or composite vertical and horizontal

sync. ouputs.

Furthermore, a composite sync. input allows, when

it is required :

- An on-chip vertical resynchronization,

- An on-chip crude horizontal resynchronization,

- An off-chip high performance horizontal resyn-

chronization by use of a simple external VCXO

controlled by the on-chip phase comparator.

EF9345

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