🚀 go-pugleaf

In <81279@ut-emx.uucp> sill@hal.as.utexas.edu (Daniel Sill) writes:

>i posted the following a few days ago:

>>i found a vga kit called "VGAKIT41.ZIP"..
...
>>1)where i can find the author: john bridges?

I believe he is on compuserve; so it should be possible to contact him via
Internet. His compuserve ID and address are probably in VGAKIT's documentation.

>>2)is there a newer version (the 4.1 ver 
>>  has a date of oct 91) ?

Yes there is, I believe it is version 5.0 dated somewhere around June 1992.

>>3)is there any other documentation on how
>> to tell what svga card is installed (and
>> info on the bank switching required) ?

Take a look at VGADOC01.ZIP at the INFO directory of simtel and its mirrors
(ftp).  It is an excellent collection of SVGA register and BIOS info for most
popular SVGA cards, along with a test program in Turbo Pascal. I believe it was 
compiled by someone on the net (from Denmark?> more than one year ago.

>PLEASE POST A REPLY HERE!
>there are many people who want the same kind of
>information...

If you want to program in SVGA for a specific card, basically the only things
you need to know are how to set the mode (with a simple BIOS call) and how 
to page a 64K bank into the video buffer at a000:0000 (by writing to some SVGA
port registers).

But of course what you want is compatibility with as many SVGA cards as
possible. This leaves you with two options: providing mode setting/page
selecting routines for a large number of card chipsets (using VGAKIT for
example) or using the VESA standard interface which is fairly straightforward.
However, not all cards have a resident VESA driver included or VESA built into
the BIOS, and some are badly programmed, although mode setting and page 
selecting usually work well.  VESA can also be slower than direct access, but
that is only relevant in code that frequently changes banks like plotting 
random pixels. VGADOC01.ZIP contains info about the VESA standard, which was
probably extracted from some version of Ralf Brown's interrupt list.

The VESA standard also includes nifty things like changing the display start
address and logical screen width, which provide for hardware scrolling, but
many VESA drivers I have seen just do nothing; the one that came with my
Trident 8900c card simply returns an 'operation succesful' code.

Hope this helps some of you. 

H. Hanemaayer
hhanemaa@cs.ruu.nl