SC126 extended char set

[sm4inv]

I seems that char 0xC3 is used to flag an extended char set.  ...

Attached a small C-program and its result.

Anyone know of any documentation on this? Are there other flags for other things, graphics etc?

I'm using Linux and MS Visual Code as editor and Putty as terminal.

Thanks

Per-Arne, sm4inv

[Alan Cox]

On Sun, 1 Aug 2021 at 09:41, sm4inv <sm4...@gmail.com> wrote:

I seems that char 0xC3 is used to flag an extended char set.  ...

Attached a small C-program and its result.

Anyone know of any documentation on this? Are there other flags for other things, graphics etc?

It depends what your terminal is set to emulate. VT220 which is what folks normally use provides multiple fonts, and some limited graphical capability.

The official DEC VT220 manual can be found here

https://vt100.net/docs/vt220-rm/contents.html

A real VT220 supports downloading  a custom font so you can sort of do graphics (when I was  a student someone wrote an awesome pacman for VT terminals)

If putty supports DRCS then you can download your own font in 8x10 pixels and upload it. The format (sixel format) is a bit convoluted but you only have to upload it at the start.

Alan

[Richard Deane]

CP/M only formally understands 7-bit characters (0-127)

There are implementations of CP/M which will allow input and output of 8-bit characters, where the meaning of a character (i.e. its display representation) is dependant on the character set selected in the PC terminal software. There are several defined "common usages" to handle characters in several non English languages.

For implementations of CP/M with memory-mapped displays (e.g. AmstradPCW) there are character roms which set the mapping for characters in the upper half of the ASCII set.

Wordstar can be configured to handle 8-bit characters for use in foreign language environments but it is necessary for the author and readers to ensure consistency in their character set mappings. As Alan mentioned the VT series terminals do make some definitions which can be used for consistency but there is no enforcement.

The 8-bit characters can be valid within the data of files but file naming and directory entries under CP/M are constrained to a subset of upper case characters (i.e. the lower half of the set). To handle international characters in file names it is necessary to redefine the US-ASCII set to mean something different for a few unused characters, to interpret them as the required special characters. This has to be common across your users, and map through to terminal software and printers. I am sure the internet has some examples.

You can see the limitation of characters in the filenames by occasionally seeing NAME.CoM instead of NAME.COM where a directory attribute (like SYS, R/W etc) has been set, and if referred to as an 8 bit character by the application will show as a lower case character.

The default CP/M implementations strip the top bit in character handling BIOS routines, but this can be adjusted by BIOS patch to enable serial transfer of 8 bit characters.

I hope these notes give you a better understanding.

Richard

On Sun, 1 Aug 2021 at 09:41, sm4inv <sm4...@gmail.com> wrote:

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