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Extended Characters and MPE

Extended characters are those which are not in the standard ASCII character set, which uses 7-bit characters and thus has values 0 to 127. ASCII Codes 0 to 31 and 127 are non-printing control characters, while codes 32 to 126 match the keys on a US keyboard ("a", "A", etc.).

Using 8 Bits Gives You an Extra 96 Characters

Since computers store characters in 8-bits, many uses have been found for the extra 128 values, most commonly for European characters such as A with Grave accent (À). Actually, only 96 of the codes are used -- values 128 to 159 are not assigned Graphics, just as 0 to 31 are reserved for non-printing control characters.

Character Sets on HP Terminals and Printers

MPE was developed with HP Terminals that use values 128 to 255 for the Roman-8 Character Set which is not compatible with anything except itself.

HP also supports a 7-bit coding scheme with ISO-7 and National Replacement Sets where punctuation characters such as { are redefined as national characters with diacritical marks.

UNIX Character Sets

UNIX is based on Teletype technology, so it frequently restricts you to 7-bit characters. When UNIX follows the lead of any CRT, it is the DEC VT-100, as in line drawing characters.

DOS Uses All 8-Bits, Some Twice Over

DOS uses the 8-bit IBM PC Extended Character Set (ECS). DOS follows the lead of IBM in using the concept of Code Pages, which provide Graphics for the non-printing control character codes as well (happy faces and other dingbats).

Microsoft Windows 3.1 Uses the 8-bit ANSI Character Set, which is incompatible with the DOS character set, but based on the ISO Latin-1 character set. DOS and Windows support Alt-Number for entering extended characters.

To further complicate things, Asian character sets require 16 bits, so Windows NT uses 16-bit Unicode internally for all character values. Unicode even has its own Web page.

Entering European Characters on HP Crt

To enter Extended Characters on an HP terminal, use the Extend Key. For an accented character, press Extend with r, t , y, u, or i for the desired diacritical mark. Then release Extend and press the key to accent. For example, is Extend u o. Some characters take only a single Extend keystroke: Extend A is . On a DOS-PC with the Reflection Terminal Emulator depress Alt-Z instead of the Extend key.
Two-Keystroke Combinations on HP Terminals
With:aeinouy AEINOUY
Extend-Ráéíóúý ÁÉÍÓÚÝ
Extend-Tàèìòù ÀÈÌÒÙ
Extend-Yâêîôû ÂÊÎÔÛ
Extend-Uäëïöü ÄËÏÖÜ
Extend-Iãñõ ÃÑÕ
One-Keystroke Extended Characters on HP Terminals

How to Insert Any Code Value into a File

In the Qedit full-screen editor, you can put any character into a file if you know the desired Decimal or Hex value. Use /list $ch $hex or /list $ch $dec to check values and use one of these methods to edit:

/set decimal on {enable 'nnn notation in strings}
/change 5 '27 * {insert Esc before column 5 in the current line}
/set mod qzmod {configure Qzmodify for Modify command}
/modify * {edit the current line}
^W? {print the character value at the cursor}
^W$ hh {put hex value hh at the cursor}
^W^P c {put character "c" at the cursor}

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