Subject: Giant LED Displays - Re: Motion video on an IBM PC/XT - Methodology
From: Grant Stockly <grant at stockly.com>
Date: Mon, 14 May 2007 21:53:37 -0800
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
At 07:40 PM 5/13/2007, you wrote:
About 3 years ago I announced to the list a little
something I'd done with
an IBM PC/XT with CGA that was unconventional for the platform
(full-motion video using stock hardware). I recently gave a talk at a
hacker convention on the complete methodology of how I did it, and the
video of that talk is now available here:
http://www.archive.org/details/8088CorruptionExplained
This whole discussion has reminded me of an unfinished project of mine, a
192x99, 19,008 pixel LED display. I have not manufactured the driver
circuits, but they have been designed.
The display is organized/refreshed as 11x1728. 8x11 characters look very
good to me, so I designed it to handle 24 wide by 9 high characters.
Here are pictures of it:
Front:
http://www.stockly.com/images2/060129-LED_Display_Front_2718.jpg
Back:
http://www.stockly.com/images2/060129-LED_Display_Back_2716.jpg
Weight of all the
legs:
http://www.stockly.com/images2/060129-Weight_of_39584_Legs_2696.jpg
As you can see from the pictures it is as big as a couch. : )
I built it in the spirit of blinkin lights for my Altair. 19008 LEDs is
2376 bytes, 71280 bytes a second at 30 frames. The altair should be able
to handle this...??? Any ideas?
Thats faster than SD 8" FDC data rate! Thats pushing an 8080 hard.
I would really love if it could handle a shade or two
of grey. : ) I'm
considering now building a driver out of an FPGA. It would be able to
handle a fast refresh rate and frame rate in order to get grey scales. I
was thinking 4 shades would be enough. The FPGA might even be able to act
as the dual port SRAM for the bitmap display? Any ideas how I should
proceed? : )
You want the CPU doing as little as possible. If at all possible the
display is refreshed by DMA from local or other memory and the CPU is
there to update/alter the display.
You can find my thread on this on USENET called
"Wall of RAM". I have
copied it here:
http://www.stockly.com/forums/showthread.php?t=21
Grant
;) if I were to do something on that grand a scale I'd consider a LED
billboard of VDM-1 (160x512) (roughly 30"x100"). Of course it would
have to use green leds.
Allison