🚀 go-pugleaf

kennehra@craft.camp.clarkson.edu (Rich"TheMan"Kennehan) writes:


>Maybe IBM defined a display memory just because they're IBM!  Think
>about it, their joysticks stink, and so do their video cards!  That's
>why we're trying to build the sprite engine!  To make up for their
>mistakes!  BTW, much of this project is weighing on whether or not the
>sprite engine can read DOS memory fast enough to send to a monitor! 
>Adding about a meg of ram to the sprite engine will drive up production
>costs considerably and might affect its marketablility!  If the sprite
>engine CAN read dos memory fast enough, then this card should'nt cost
>more than 50 bucks!!!  And that would be GREAT!!!

     The video refresh circuitry has to constantly be reading the
     sprite data from memory, 70 times per second according to your
     design.  Now, we all know that 2 devices *CANNOT* read/write
     data on the bus at the same time.... which means that your sprite
     engine would have control of the bus almost all of the CPU time, so
     you would not be able to do any other processing at all!!  The idea
     of video memory on the card is to prevent this from happening.
     So, plan on using on-card memory.... You would want to use SRAM,
     VRAM, and DRAM in that order for performance and ease of design. But,
     for cost, you would want to use DRAM, VRAM, SRAM in that order.  
     Basically, you guys will need to use DRAM since you should have
     quite a bit o' memory on that sucker. 
     I'd recommend figuring out exactly how the VGA card works, get to
     know what every little feature of it does... and then, you'll know
     what you need to do to build the sprite engine.
-- 
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  John A. Slagel, email: jas37876@uxa.cso.uiuc.edu