> The question is whether to put the video on the motherboard or not.
>
> Many (most?) of the people interested in this board want to make a
> nice fast workstation. Any good workstation has fast, big colourfull
> video. The issue here is just how do you get that glossy video
> and how much to pay for it.
I agree. Although the bombs were very small (if not inexistent)
my idea to have no video on board haven't found friends...
> Its true that the video will be the most expensive optional part or
> the board, coming in at about $100. I offer some alternatives.
Yes, but a mid-class ISA card costs the same.
> First, video on the board:
>
> * 1 MB of Video RAM (supports 1024x1024 8-bits per pixel;
> better resolutions if 1,2 or 4-bits per pixel are used)
> or
> 2 MB of Video RAM (supports 1280x1024 8-bits per pixel)
> * TI 34076 RAMDAC (has pixel multiplexing, 256 out of 2^16 colors).
> * NSC 1882 (generates Video sync, and DMA requests.?)
1024x1024 is a bit unusual :-) Better 1024x768. That wastes ~25% of
the VRAM. 1280x1024 wastes ~33% of the 2 Meg required.
Why not 1152x900 ? That would utilize 99% of 1 Meg VRAM.
> If the peripheral controller is a 3730, then special logic would be
> provided to generate the shift register load cycles for the VRAM,
> and, of course the main CPU does the video support. If the peripheral
> controller is the 3041, then the VRAM may be connected to either
> processor. If it was connected to the main CPU, the 3041 could still
> access the VRAM anyhow, albeit a little slower. The 3041 could
> generate the special VRAM cycles.
Generating the shift register load and clocking out that stuff
could be realized by some GALs.
> Advantages of video on the motherboard:
> * High bandwidth direct connection to CPU
> * Linear memory organization (good for software)
> Disadvantages:
> * Adds significant cost to the end price of the motherboard.
>
> For those that don't want the video section, the motherboard could
> be sold with empty sockets for the whole video section. A separate
> video add-on package containing the chips to plug in could be put
> together.
This is a good solution. I like it !
> Video on a VESA or local bus connector:
>
> (I understand that VESA and local bus are the same thing; correct me
> if I'm wrong.)
Correct me too, please :-)
> Advantages of VESA video:
> * High bandwidth direct connection to CPU
> * Linear memory organization available
> * Cards available to do this already
> * No work for us to design video
> Disadvantages of VESA video:
> * CPU is assumed to be an x86 (hard work to connect to a R3000)
> * VESA is apparently going to die soon.
> * VESA and its replacement, PCI, require licenses to use.
> * Higher total cost than motherboard solution
The fact that VESA is on the way to die should be enough
reason not do use VESA video cards.
> Video on the ISA bus (assuming there is one):
>
> Advantages of ISA video:
> * Cheapest video solution
> * ISA easy to implement
> * Accelerator cards available that support reasonable speed
> * Almost everyone already has a ISA video card
> * Software already exists
> * No work for us to design video
> * Cards will be around for a while (ISA will not die soon)
> Disadvantages of ISA video:
> * Still not as fast as direct connect video, even with accelerators
> * Higher total cost than motherboard solution (if using fast card)
> * Very complicated interface (VGA)
The greatest disadvantage of ISA video cards is loooow speed for
nearly the same price we would pay for *fast* on-board video.
> No video at all:
>
> Advantages:
> * Cheapest solution of all
> Disadvantages:
> * Must have external terminal
> * Not as cool!
Hmm. No video at all can't be a solution...
> My personal opinion is that the video should be on the motherboard as
> an option. That is, the video designed and tested, but motherboards
> shipped with empty sockets. I'm one of those that want the really cool
> huge colour monitors.
I don't need huge colour monitors. I'm satisfied with a 17" monochrome
display. But I don't mind if it's colour :-)
Andy
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