Can you build a IIGS slot based DVI video card for $10 (USD)? Yes, it can be done.
Would you want to build a IIGS slot based DVI video card for $10 (USD)? Now, that's a more intersting and difficult question to answer. The dury is still out on that one.
For all you sensationalists out there, note that this is the build price and not the sell price.
https://lukazi.blogspot.com/2025/07/cheapskatedv-xenithdv-prototype.html
Cheers,
Alex.
Hi Lukazi -
I've looked at your website and this project is fascinating.
But be very, very careful with the input voltages to your 3.3V logic. Unless the "improved ESD protection" in your IC is specified for being operated with 5V logic swings, there is a lurking danger of CMOS latch up.
The relevant information is in the "Absolute Maximum Ratings" section of the datasheet. Look for what it specs for the input voltages vs. the 3.3V and GND supply pins. I don't have the time to do this for you.
CMOS ICs which tolerate excess input voltages higher than their positive supply pin or lower than their negative supply (often, the "ground") pin are quite rare. It can be done but takes a lot of area for the added protection rings in the pad circuitry, and die area costs money, so IC manufacturers tend to avoid these extra features.
What you could do, to make this design bulletproof, is to add a series resistor of ~390 Ohms to each input pin and then a small signal Schottky diode at the pin (diode anode) to the positive supply voltage pin (diode cathode) of the IC. This also protects the IC against sluggish rise time of the 3.3V supply.
- Uncle Bernie
Does this card support properly all //GS graphics capabilities? Could you show a close-up picture of the same //e game screen seen now from a distace and produced by your card, and optionally by the SONY PVM, provided the CRT monitor is connected to the //GS RGB port. What is the delay between powering on and the DVI video ouptut?
These are fascinating. Even if you end up having to add 74LVC245s, the capabilities are very nice. I'm really intrigued by the one for the //e AUX slot, as that kills two //e needs with one card. How much extended memory does it offer? Something that did 4MB or even better 8MB or 16MB would be very nice.
Thank-you to eveyone's comments. Out of this I have a few things to go and investigate. I've done a lot of projects where I have obtained the "Proof of Concept" stage but have found the project to be not worth pursuing. At this stage I've only implemented bits and pieces aimed at determining if I'm going to get any show stoppers. So far so good. I've still got some IIGS timing issues which I'm trying to get my head around. When I get all that sorted, I agree, it will be good to video the boot process and work out the monitor lag. When I'm happy with the IIGS RGB colour models I'll try to provide some close up examples. The current DVI output of HGR/DHGR images look pretty much the same as my VGA solutions. I've got close up examples on my previous blog posts. So far I have been unable to represent online with pictures of how good these images look in person. I'm especially loving my iPad retina display solution. However, I don't want people taking my opinons since they are obviously going to be baised. I'll leave it to the reviewers. Thanks. Alex.
G'day Alex,
I'm seriously impressed with what you have achieved thus far and am really excited to watch your progress.
Fingers crossed that you get all the "niggles" ironed out and we can look forward to another means of displaying our beloved Apple II's on a modern display. I am particularly interested in the IIgs implementation, as this is the area where the least number of solutions have been found and/or are currently available.
Great work!
Mike