Are there any recommended made to oder PCB services if you just want a card? Googling around seems to be a lot
of options all over the world but maybe some HNers have experience with some of them.
HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
11–20 of 55 posts
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#12"the brown colour is displayed incorrectly as dark yellow"
I understand what it means in an RGB context but it is the first time I seesomeone mentionning dark yellow as a color.
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#13I've worked on something similar while in college. HDMI is actually a fairly simple protocol, based on VGA. It still has scanlines and such, but the signals are digital instead of analog. So instead of a RAMDAC, you have the HDMI encoder chip. You typically need control some i2c interface to set the HDMI encoder chip in the correct mode, but that's about it.
How does its complexity compare to DisplayPort?
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#14I've worked on something similar while in college. HDMI is actually a fairly simple protocol, based on VGA. It still has scanlines and such, but the signals are digital instead of analog. So instead of a RAMDAC, you have the HDMI encoder chip. You typically need control some i2c interface to set the HDMI encoder chip in the correct mode, but that's about it.
I remember i2c support was added to the Linux kernel. I never understood what it is. Next in line is BPF, which is also unclear.
If you're talking about (e)BPF, the (extended) Berkeley Packet Filter, the easiest way to think about it is like a tiny virtual machine running inside the kernel, which can execute "simple" commands that would otherwise be very slow or very complex from within userspace. The traditional example would be counting the number of packets being sent out by a network interface. But it turns out that eBPF is massively more general purpose than that, allowing people to develop all kinds of monitoring applications.
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#15"the brown colour is displayed incorrectly as dark yellow" I understand what it means in an RGB context but it is the first time I seesomeone mentionning dark yellow as a color.
There's a lot to say about the color brown :-) https://www.youtube.com/watch?v=wh4aWZRtTwU
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#16I imagine a PC with a Graphics Gremlin and either a Snark Barker or Snood Bloober for audio, is going to be quite the hipster toy to have, one of these days .. all this great old, retro, PC hardware designs!
I refuse to believe Snark Barker and Snood Bloober are real device names, what a funny time in computing that was.
They're modern clones of the SoundBlaster 1 card (a real late-80s sound card).
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#17I've worked on something similar while in college. HDMI is actually a fairly simple protocol, based on VGA. It still has scanlines and such, but the signals are digital instead of analog. So instead of a RAMDAC, you have the HDMI encoder chip. You typically need control some i2c interface to set the HDMI encoder chip in the correct mode, but that's about it.
Based on what you said, you didn't actually look at HDMI protocol, only the protocol exposed to your HDMI encoder chip. You could have such a protocol on Thunderbolt 3 encoder chip.
FWIW, yes HDMI is still pretty simple, but not as simple as you describe it. Even though there are 3 pairs of data it's not one pair R, one pair G, one pair B (highest-bandwidth HDMI uses 4 pairs), it's just one data bus. The data pairs aren't only used for data colors, but also conveys audio, and info frames (which will include various stuff like HDR or VRR metadata). Of course there is the matter of DRM: the content will often be encrypted (but negotiation of that encryption happen separately, over I2C)
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#18Related development for those interested in using old hardware with new displays. There is this ISA HDMI addon card in development that will add HDMI port to your existing old display card: https://www.vogons.org/viewtopic.php?t=92512
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#19I've worked on something similar while in college. HDMI is actually a fairly simple protocol, based on VGA. It still has scanlines and such, but the signals are digital instead of analog. So instead of a RAMDAC, you have the HDMI encoder chip. You typically need control some i2c interface to set the HDMI encoder chip in the correct mode, but that's about it.
Based on what you said, you didn't actually look at HDMI protocol, only the protocol exposed to your HDMI encoder chip. You could have such a protocol on Thunderbolt 3 encoder chip. FWIW, yes HDMI is still pretty simple, but not as simple as you describe it. Even though there are 3 pairs of data it's not one pair R, one pair G, one pair B (highest-bandwidth HDMI uses 4 pairs), it's just one data bus. The data pairs a…
That's only the case in the (relatively) shiny new 2.1 spec with FRL. Prior versions are TMDS with 3 channels for red, green, blue, along with a clock. The audio and InfraFrames slot into the data islands in blanking periods on those signals.
Re: HDMI ISA graphics card for vintage PCs by improving the Graphics Gremlin
#20I've worked on something similar while in college. HDMI is actually a fairly simple protocol, based on VGA. It still has scanlines and such, but the signals are digital instead of analog. So instead of a RAMDAC, you have the HDMI encoder chip. You typically need control some i2c interface to set the HDMI encoder chip in the correct mode, but that's about it.
Based on what you said, you didn't actually look at HDMI protocol, only the protocol exposed to your HDMI encoder chip. You could have such a protocol on Thunderbolt 3 encoder chip. FWIW, yes HDMI is still pretty simple, but not as simple as you describe it. Even though there are 3 pairs of data it's not one pair R, one pair G, one pair B (highest-bandwidth HDMI uses 4 pairs), it's just one data bus. The data pairs a…
While that's true, you really only need to blast out RGB data to get an image on screen. Most of what you are talking about is layered on top and optional.
I did a tiny HDMI implementation in an FPGA for a project, the TMDS implementation was what took the longest.