World's worst video card? The exciting conclusion!
Here's part 2!
Here I talk about how VGA uses analog RGB signals to send different color pixels to the monitor. I use an EEPROM to store an image and build a simple digital-to-analog converter to generate the color signals to successfully display an image.
As always, I appreciate any feedback or issues you find. I'm at VidCon for the rest of the week, so I don't have an ability to record anything until next week. So fingers crossed there aren't any major problems with the video.
World's worst video card? The exciting conclusion! (YouTube)
Comments (12)
So I'm really curious... if you change the 10MHz clock to a 40MHz clock, and swap the EEPROM (150 ns) out for a SRAM chip, like the 62256LP-70 (70 ns), could you achieve the 800x600 resolution over VGA and eliminate the black lines that show up in your final product? I'm building both your 8-bit computer, and also working on the 6502 project, and I'd love to put an 80x24 display instead of the LCD screen. It seems like that would be doable, but I may be missing something.
I should also mention, even at 4 bpp, it would take 240K bytes of RAM to store an 800x600 screen. That would fit in a 256K RAM chip, but wouldn't be addressable by either of the computer projects. I'd be more interested in character maps and storing 80x24 characters in video RAM. I'm thinking out loud a lot :)
Hey, if anyone is interested I laid out a PCB of the breadboard clock in KiCad. I can make the files available if anyone wants them. It is organized "true to" the breadboard style. I know it could be much smaller or optimized with SMD parts but I thought it would be cool to honor Ben's layout. Let me know, thanks.
This is fascinating, I would love to experiment with digital electronics but I wouldnt know where to start!
You could start, like he did, by building a clock circuit.
Oh my. I am so elated to be immortalized in this amazingly cool way. Thank you for yet another amazing video and the cool way to thank your patrons.
Thank you Ben! Very informative video as always. I particularly appreciate that you don’t edit out simple mistakes like connecting the eprom to the incorrect pin of the timing counter circuit.
Excellent video! You make this topic much more approachable than any other tutorial. Not sure how much this matters, but the famous test image of "Lenna" has a bit of controversy around it related to sexism (she was a playboy centerfold). You may want to reconsider your thumbnail.
I can't wait to see what your next project will be. May I suggest adding a logic unit to your computer in addition to the arithmetic unit it currently has? I have a good idea how that could be implemented using only 4-to-1 multiplexers and a few 4-bit registers. It can be pipelined with the existing ALU as well. In fact I plan on building a slightly enhanced version of your computer using this combined logic+arithmetic unit.
I personally did not see any issues. Very interesting, thanks!
This series was really amazing. You are doing an excellent job with breaking down the steps and explaining each. I learned plenty from it. Thank you!
That was delightful, Ben. Thanks! The foreshadowing at 3:04 is exciting.