From: estaucl@csv.warwick.ac.uk (Mr I Coggins)
Subject: Beyond 640K, Trident 8900, and lots more 8)
Organization: Computing Services, University of Warwick, UK
Lines: 48
NNTP-Posting-Host: nutmeg.csv.warwick.ac.uk
Keywords: Ram,Trident,Interrupts

Hi,

I have a few enquiries about PC's and compatibles in general.. Some software
others hardware orientated.. (Probably the wrong newsgroup .... as everyone 
claims..)

Anyway..

1) Does any one happen to have the board jumper details for a Trident 8900
SVGA graphics card (1MB) or even what the dip switches do on the end.. Mine
already works fine (albeit slow) and after having blown up a monitor I found 
out which switch controlled the interlace/non interlace facility.. 

But I'm curious as to why there are 8 dip switches on the card with apparantly
little use..

2) Secondly, does anyone know why Commodore had to be so crazed in their design
of the PC-40 motherboard with respect to the RAM.. (IE 512 + 512 or 640 +0K) ??

3) Can anyone supply pin details for the expansion ports for a pc (8 or 16 bit
) .. or even a sample circuit to cause an irq when a button is pressed...
(Yeah I know its a piece of cake.. I'm lazy 8)

4) Software wise.. Anyone care to divulge some tips on accessing expanded RAM
on a PC (from a program written in Turbo C++).... 

For instance, using farcoreleft() and coreleft() return only memory available
from the base 640K regardless of combinations of EMM386 etc etc...
What I want is to be able to use the RAM above and beyond the 1MB boundary...

I'm not certain whether farmalloc / new actually uses it anyway but I'll 
suspect not .. 

5) Also.. what half brained wit created DOS so as not to be re-entrant??????
   As a follow on, does anyone have any comments about the use of DOS calls
   0 to 0C from within a DOS interrupt? Ie will changing the stack size on
   entry be of use.. Two articles I've read on the subject have given 
   conflicting views... Does anyone have any views on writing direct to
   screen memory in terms of portability?

Many thanks..
Gotta go, bars closing soon 8)
Cheers
Ian