Date: Fri, 18 Feb 94 10:12:17 -0500
From: DJ Delorie <dj AT ctron DOT com>
To: dridge AT mit DOT edu
Cc: csaba AT vuse DOT vanderbilt DOT edu, dridge AT mit DOT edu, djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: Mach32 driver, Diamond Stealth


> >card with the fastest bus interface. Many times accelerated cards are in
> >fact slower than simple "dumb frame" SVGA cards (i.e. ET4000, etc..)
> what kind of card has an ET4000, etc. in it?
> I am primarily concerned with 24bit color, at up to at least 640x480,
> very preferably up to 800x600.

If you need more than 1M of VRAM, the ET4000 won't cut it.  

> >with regard to direct video memory access from the CPU. A few months ago
> >DJ circulated a video RAM access speed benchmark program and asked the
> >readers of the group to run it on their systems. Check the archives of
> >the mail group for the results.
> where are these available?

I have the binary/source for the benchmark.  Basic summary: for
system->video transfers in 320x200x256 mode, the fastest *system* was
an ET4000W32 in a 486/50 (not a DX2!), at 27.7Mb/s(*).  Next best, in
a 486-DX2/66, was the ATI Ultra Pro (18.8 Mb/s).

Top results (sys->sys, sys->vid, etc) for 32-bit accesses:

                        s->s    s->v    v->s    v->v     s->     v->     ->s     ->v
486DX2-66-Geno7900	31,098   8,711   5,254   3,510  45,257   5,918  52,022   9,426
486DX2-66-Dell-S3	23,211   9,737   4,410   2,980  30,763   4,865  64,872  12,106
486DX2-66-Stealth-VLB   12,951   9,473   3,737   3,057  34,748   4,963  26,113  11,080
486DX2-66-Dell          39,591  10,995   4,378   3,033  45,761   4,715  65,075  12,147
486DX2-66-Stealth-VLB   31,542  10,130   4,426   3,057  45,700   4,995  43,421  11,074
486DX2-66-Geno8500      20,699  11,204   4,886   4,141  36,792   6,254  37,386  13,290
486DX2-66-ET4000AX-VLB  15,782  12,711   5,542   4,896  33,738   7,571  28,320  15,998
486DX2-66-ATIUltraPro   36,220  18,313   8,882   5,184  45,074  10,345  65,066  21,786
486DX2-66-ET4000W32     12,869  18,857   7,369   7,712  34,217  13,983  23,677  26,678
486-50-ET4000W32(*)     31,926  27,779  13,256   9,574  35,769  16,388  50,104  38,882

The s->s numbers give the performance of CPU/memory (movsd).

(*) This system exceeded the 40Mhz spec for the local bus.  At DX2/66 speed,
the benchmark would have been 18.4 MH/z

> Will I be able to drop the card into a 24-bit mode, hopefully with
> all 3 bytes contiguous (or padded to 4 bytes), and just blast across?
> Will DJGPP/GO32 be able to handle it, or will I have to write my own
> drivers, etc.?

go32 can handle that.