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Diffstat (limited to 'usr.sbin/pcvt/Misc/Doc/Charsets')
| -rw-r--r-- | usr.sbin/pcvt/Misc/Doc/Charsets | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/usr.sbin/pcvt/Misc/Doc/Charsets b/usr.sbin/pcvt/Misc/Doc/Charsets new file mode 100644 index 0000000..b30dd8a --- /dev/null +++ b/usr.sbin/pcvt/Misc/Doc/Charsets @@ -0,0 +1,99 @@ + +I. Character Set Selection on VT220 Terminals +================================================== + + +name C0 GL C1 GR + +---+ +-------------------+ +---+ +-------------------+ + |00h| | | |80h| | | +range | | | | 20h .. 7fh | | | | | a0h .. ffh | + |1fh| | | |9fh| | | + +---+ +-------------------+ +---+ +-------------------+ +length 32 96 32 96 + + /\ +SECOND /||\ "lock"- or "single"-shift one set of G0, G1, G2 or +STEP || G3 into one of the "displayable" charactersets GL + || or GR. (escape) sequences are: SI, SO, ESC ~, ESC n, + || ESC }, ESC o, ESC |, ESC N and ESC O. + + +----+ +----+ +----+ +----+ +name | G0 | | G1 | | G2 | | G3 | +length |(96)| |(96)| |(96)| |(96)| + +----+ +----+ +----+ +----+ + + /\ + /||\ designate a hard or a soft character set as + || one of G0, G1, G2 or G3, used escape sequences +FIRST || are, ESC ( X, ESC ) X, ESC * X and ESC + X - where X is +STEP || B for ascii, < for supplemental, 0 for special, A for + || british, 4 for dutch, C and 5 for finnish etc. etc. ... + || + + +-----+ +------------+ +--------+ +-----------+ +------------+ +name |ascii| |supplemental| |special | | national | |downloadable| + | | | graphics | |graphics| |replacement| |characterset| +length | (96)| | (96)| | (96)| | (96)| | (96)| + +-----+ +------------+ +--------+ +-----------+ +------------+ + + \-------\ /----------/ norway/danish + | dutch + together, this is also finnish + referred to as the french + multinational character french canada + set (power on default german + on a dec vt220) italian + spanish + swedish + swiss + + +II. Emulating Character Set Selection +========================================= + +MDA/HCG/CGA: + + just a partial emulation is done, because these boards don't allow + downloadable charactersets. some characters simply don't display + because they are not in the characterset roms on the video board. + + if you want to change the mapping, have a look at the default tables + in pcvt_tbl.h. + +EGA/VGA: + + these cards have provisions for downloadable charactersets and so + many vt220/vt320 charactersets are fully supported: + + - US Ascii + - DEC Supplemental + - DEC Special Graphic + - DEC Technical + - ISO Latin-1 + - Downloadable + + when the emulator is started, it behaves initially similar to + the MDA/CGA/HCG method described above. + + when a second (special) characterset for a given screen resolution + is loaded via the "loadfont" utility, the emulator detects this fact + and uses from then on extended tables to access the second charset + as an upper half 512 characterset in terms of ega/vga speak. + + from this time on, vt220 downloadable fonts are usable. + + the organization of this extended characterset is as follows: + + 0x00 ... 0x1f C0 display function fonts + 0x20 ... 0x3f C1 display function fonts + 0x40 ... 0x9f fonts for DEC Supplemental, DEC Special + Graphic, DEC Technical and ISO Latin-1 + 0xa0 ... 0xff VT220 Downloadable Font + + the mapping between vt220 charactersets and the charactersets inside + the ega/vga is done by tables found in the file pcvt_tbl.h. + + there is a MSDOS fonteditor called "EVAFONT" available on the + SIMTEL-20 archive, which i used to edit the character sets in the + distribution. + |
