roland@dna.lth.se (Roland Mansson) (01/21/91)
We are working on a project where we need to display (>)500
different characters on the screen. We are not sure on the
way to go now, should we use graphics or textmode?
According to some documentation it's possible to change the
fonts used in the textmode, and in some places it says that
only the last 128 characters is placed in ROM (i.e. possible
to change). Is it possible to change the .CPI files to get
an alternative font? We can see advantages and drawbacks in
both approaches and have a fairly good knowledge about
graphic oriented displays, but we would like to have some
tips and advises on a textmode solution, a topic seldom
covered in PC-literature. On a "Hercules plus" card this is
easily done, but how about the other cards? Its obviously
done in some programs, for example Norton Utilities displays
a mousecursor in textmode drawn by changing the textfont on
the fly.
Is it possible, we probably must have 2 fonts and switch
them in and out?
How is the .CPI files used?
Has someone done anything similar?
Thanks in advance
Joakim Bengtson & Lars Sigebo
Lund University Computing Center
--
Roland Mansson, Lund University Computing Center, Box 783, S220 07 Lund, Sweden
Phone: +46-46107436 Fax: +46-46138225 Bitnet: roland_m@seldc52
Internet: roland.mansson@ldc.lu.se or roland.mansson%ldc.lu.se@uunet.uu.net
UUCP: {uunet,mcvax}!sunic!ldc.lu.se!roland.mansson AppleLink: SW0022ts@uwasa.fi (Timo Salmi) (01/23/91)
In article <1991Jan21.144508.2272@lth.se> roland@dna.lth.se (Roland Mansson) writes: >We are working on a project where we need to display (>)500 >different characters on the screen. We are not sure on the >way to go now, should we use graphics or textmode? > >According to some documentation it's possible to change the >fonts used in the textmode, and in some places it says that >only the last 128 characters is placed in ROM (i.e. possible : You might find the reference information on fonts in faqpas.txt in /pc/ts/tsfaq16.arc of some interest. ................................................................... Prof. Timo Salmi (Moderating at anon. ftp site 128.214.12.3) School of Business Studies, University of Vaasa, SF-65101, Finland Internet: ts@chyde.uwasa.fi Funet: gado::salmi Bitnet: salmi@finfun
frisk@rhi.hi.is (Fridrik Skulason) (01/24/91)
In article <1991Jan21.144508.2272@lth.se> roland@dna.lth.se (Roland Mansson) writes: >We are working on a project where we need to display (>)500 >different characters on the screen. We are not sure on the >way to go now, should we use graphics or textmode? I assume you need 500+ different characters on the screen at the same time, not just a simple swap of character sets. The answer is: It depends .... I would recommend using textmode, simply because of speed, but there are a few problems. The solution depends on the display cards you use. IF you are using original CGA, MDA or Hercules cards, forget it - you cannot do it. If you are using the new cards from Hercules, where they use 14 bits per character instead of 8 it is easy. The interesting solution is when you are using the VGA card, which is more-or-less the standard card today. It is easy to redefine characters on the EGA/VGA - any single character or a block of them can be redefined with a short piece of code - something like this: MOV CX,29 ; number of characters to change MOV DX,139 ; starting character MOV AX,1110H ; change it MOV BH,16 ; bytes per character MOV BL,0 ; block to load INT 10H MOV AX,1103H ; and select block 0 XOR BX,BX INT 10H However - you can normally only display 256 different characters on the screen at the same time. There is a solution, though, provided you do not need more than 512 different characters on the screen. Every character on the screen is represented by 16 bits - normally 8 are used to select the character, and 8 are attribute bits. It is possible to change that - using one of the attribute bits to select a block of characters. The code is something like this... MOV AX,1103H MOV BL,0CH Then a character from block 0 will be selected when attribute bit 3=0, otherwise a character from block 3 will be selected. You just need to set up the bitmap for the new 256 characters (have fun - I think I have a character mode font editor somewhere if you want it) and load block 3. The drawback of this method is the loss of one colour - you get only 8 colours, instead of 16. -frisk ---- Fridrik Skulason University of Iceland | Technical Editor of the Virus Bulletin (UK) | Reserved for future expansion E-Mail: frisk@rhi.hi.is Fax: 354-1-28801 |