VT100.net VT330/VT340 Programmer Reference Manual

8 Load Command

Using Your Own Character Sets

The VT300 lets you designate up to four character sets to use in ReGIS. The alphabet 0 set (A0) can have up to 192 characters, all others can have up to 96 characters. You assign and select these character sets by number.

Number Character Set
0 Any one of the terminal's built-in sets (such as ASCII or ISO Latin-1 supplemental graphic)
1 to 3 Up to three sets that you load into the terminal from the host system

You use the load command to select, load, or reload sets 1, 2, and 3. You cannot use the load command to load character set 0. Set 0 is reserved for one of the terminal's built-in sets. See Chapter 7 for information on loading built-in character sets.

There are three options to the load command.

Select character set Assigns a number to the set you want to load.
Specify name Assigns a name to the set selected with the select character set option.
Load character cell Loads a character into the set selected with the select character set option.

Select Character Set

You use this option to assign a number to a character set you want to load into the terminal. You can select 1, 2, or 3. You use the following format for the select character set option.

L(A<1 to 3>)

where

L identifies a load command.

A identifies a select character set option.

<1 to 3> is a number to assign to a character set loaded from the host system.

After you select a character set number, you can use the other load command options to name the character set and load the characters. All load commands apply to the character set with this number, until you select another number. However, you can use other types of ReGIS commands without affecting the character set selected for loading.

You load characters into the character set by using the load character cell option. You can load characters into the character set as needed. You do not have to load the complete set at one time.

NOTE: You can select character set 0, but you cannot load it.

Specify Name

This option lets you specify a name for the character set selected with the select character set option. You can use up to 10 characters in the name. You use this name for report commands (Chapter 10), to report the name of the currently selected loadable set. You use the following format for the specify name option.

L(A'<name>')

where

A identifies a specify name option.

' ' are single or double quotation marks that enclose the character set name.

<name> is a name to assign to the currently selected character set. You can use up to 10 characters in the name.

You can use the specify name and select character set options together. That is, you can assign the name and number of the character set at the same time. Make sure you use the select character set option first in the command. Otherwise, ReGIS assigns the name to the character set already selected, not the character set you are selecting.

Load Character Cell

These arguments let you design and load a character into the terminal. ReGIS loads the character into the set selected with the select character set option. You use the following format for the load cell option.

L"<character>"<hex pairs>

where

" " are single or double quotation marks that enclose the call letter to use for the character cell you are loading.

<character> is one ASCII character to use as a call letter for the character cell you are loading.

<hex pairs> is a hexadecimal code that defines the appearance of the character cell. You use a pair of hex values for each row of the cell (up to 10 rows).

First, you assign a call letter (<character>) to the cell. You use the call letter to select the loaded character set in text commands. You can use any single ASCII character for the call letter, including a number or space. However, there is no relationship between the shape of the call letter and the character you are loading.

Next, you define how the loaded character will look. Each character cell has 80 pixels in a 8 × 10 array. This size matches the unit cell size for a standard S1 character cell (Table 7-1). You cannot define a character larger than the 8 × 10 array.

You use hexadecimal codes to define which pixels are on and off when you display the character. Table 8-1 lists the bit pattern for each possible hex code. A 1 bit turns a pixel on, and a 0 bit turns a pixel off. Each hex code defines a 4-bit pattern. You use two hex code values to define a row of 8 pixels. You can define all 10 rows in the character cell.

Table 8-1 Hex Code Table
Hex Code Bit 1/5 Bit 2/6 Bit 3/7 Bit 4/8
0 0 0 0 0
1 0 0 0 1
2 0 0 1 0
3 0 0 1 1
4 0 1 0 0
5 0 1 0 1
6 0 1 1 0
7 0 1 1 1
8 1 0 0 0
9 1 0 0 1
A 1 0 1 0
B 1 0 1 1
C 1 1 0 0
D 1 1 0 1
E 1 1 1 0
F 1 1 1 1

You build the cell from the top down. The first hex code value for a row controls the pattern for the four left pixels. The second value controls the pattern for the four right pixels.

Example

If you use more than two hex values, ReGIS proceeds as if you used a comma after each pair of values. If you use only one hex value or end up with one, ReGIS assumes the first hex value is 0 and sets the first 4 bits in the row to 0 (off).

You do not have to define every row in a cell. However, you must define the following rows.

ReGIS assumes that any undefined rows at the bottom of the cell are blank. Figure 8-1 shows some examples of loaded characters and their hex codes.

Figure 8-1 Example of Load Character Cell Argument
COMMANDS
 
(A)
(B)
(C)
(D)
(E)
(F)
L(A3"alpha")
"S" 00,14,3E,54,3E,15,3E,14
'c' 4,E,15,15,15,E,4
'C' FF,89,EB,81,E3,81,EB,89,FF
"b" 7F,41,41,41,41,49,55,55,55,63
'1' 0,1C,1C,1C,7F,3E,1C,8
"." 0,1F,8F,47,29,10,28,44,82;

Load Command Summary

Table 8-2 is a summary of the L command options, including any default values.

Table 8-2 Load Command Summary
Option Default Description
(A<1 to 3>) 1

Select character set
Selects one of three loadable character sets to use for any following load commands.

(A"<name>") " "

Specify name
Selects a name of up to 10 characters for the currently selected loadable character set. You can use this option with the select character set option:
(A<1 to 3>"<name>").

"<ASCII>"<hex pairs>

Load character cell
Loads a character into the currently selected loadable set.

<ASCII> is an ASCII character you use to select the loadable character in other commands.
<hex pairs> define the bit pattern for each line of the character.