9

Display Clear

Data stored in the Character RAM, Control Register, and

Attribute RAM will be cleared if the clear (CLR) is held

low for a minimum of 10 µs. Note that the display will be

(20hex) is loaded into all character RAM locations and

00hex is loaded into all Attribute RAM/Control Register

memory locations.

Data Entry

Figure 2 shows a truth table for the HDLX-2416 display.

cursor select (CU) to logic 1 will enable ASCII data

loading. When cursor select (CU) is set to logic 0, data

will be loaded into the Control Register and Attribute

information into the display. Data will be latched into

write cycle to ensure that correct data is stored into the

display. Data can be loaded into the display in any order.

right most display location.

CUE

BL

CLR

WR

CU

Function

0

1

1

Display ASCII

1

1

1

Display Stored Cursor

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

0

Reset RAMs

Blank Display but do not reset

X

0

1

RAMS and Control Register

Extended

Intensity

Master

Digit

Digit

Write to Attribute RAM

0

0

0

Functions

Control

Blank

Blank

Cursor

and Control Register

Disable

Disable 0

0

0 =

000 = 100%*

0 =

Digit

Digit

0

0

1

Enable

001 = 60%

Display

Blank

Cursor

blanked

010 = 40%

ON

Disable 1

1

011 = 27%

X

X

1

0

0

0

1 =

100 = 17%

1 =

Digit

Digit

being blanked.

0

1

0

Disable

101 = 10%

Display

Blank

Cursor

110 = 7%

Blanked

Disable 2

2

111 = 3%

Digit n

Digiit

Digit

0

1

1

Always

Blank

Cursor

Enabled

Disable 3

3

1

0

0

Digit 0 ASCII Data (Right Most Character)

1

0

1

Digit 1 ASCII Data

X

X

1

0

0

0

Write to Character RAM

1

1

0

Digit 2 ASCII Data

1

1

1

Digit 3 ASCII Data (Left Most Character)

1

X

X

X

X

1

X

1

X

X

X

X

X

X

X

X

X

X

X

No Change

X

X

1

Figure 2. Display truth table.

0 = Logic 0; 1 = Logic 1; X = Do Not Care; * 000 = 27% for HDLU-2416

Cursor

When cursor enable (CUE) is a logic 1, a cursor will be

displayed in all digit locations where a logic 1 has been

stored in the Digit Cursor memory in the Attribute RAM.

The cursor consists of all 35 dots ON at half brightness.

A flashing cursor can be displayed by pulsing CUE. When

CUE is a logic 0, the ASCII data stored in the Character

RAM will be displayed regardless of the Digit Cursor bits.

Blanking

Blanking of the display is controlled through the BL input,

the Control Register and Attribute RAM. The user can

achieve a variety of functions by using these controls

in different combinations, such as full hardware display

blank, software blank, blanking of individual characters,

and synchronized flashing of individual characters or

entire display (by strobing the blank input). All of these

blanking modes affect only the output drivers, main-

taining the contents and write capability of the internal

RAMs and Control Register, so that normal loading of

RAMs and Control Register can take place even with the

display blanked.