From: willmore@iastate.edu (David Willmore) Subject: Re: Need help with programming ET4000 Date: Fri, 21 Aug 1992 19:10:30 GMT
burkert1@platon.fmi.uni-passau.de (Klaus Burkert) writes:
>On VGA-chips the registers are 'indexed', because alot of them have to fit
>in very few port-adresses (from memory the ET4000 has about 80 registers).
>These registers are accessed as follows (for your example):
>write the desired index (33h) to port 3d4h
> (mov dx,3d4; mov al,3; out dx,al)
>and access the indexed register at port 3d5h.
>That's the whole magic with indexed registers.
>Ciao, Klaus.
This is what I was looking for. The idea of indexing registers on a vga
card is repulsive, but "do as the romans do." I have programed on other
indexed i/o systems before and it hasn't taken much time for me to get
used to this one. I already have the code to to Tseng 4000/3000 detection
running. I'll get the rest done soon.
I would like to thank everyone for their help. I have received numerous
replies. Many of them were asking me to forward them what I do find.
Since there is so much need, I am planning on writing a toutorial in both
basic and pascal to show people how to program graphics and text on the
Tseng family. I'll also include C if I get my compiler soon. I hope.
Thanks again!
--David Willmore
willmore@iastate.edu